Bass project for my kid

Bass project for my kid

I've got an 11 year old who is interested in playing the bass guitar.

I bought him a used Peavy KB 60 keyboard amp to get started and to see if it
was what he wanted to do. It is.

Problem is, the amp is too heavy to drag to a buddy's house for jamming, so
I looked around my shelf and found a Heathkit EA-3 mono tube amplifier that
I can mate with a 10 inch speaker. The amp has a pair of EL84s in push-pull
with an ultralinear OPT - for 14 watts RMS.

The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB. Would
I be right in assuming that the -3 dB point ought to be low enough for bass
amp use?

The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
better off with an SPL of 93?

I found a schematic for a Gibson GA-14 that looks just about perfect.

Any thoughts suggestions?

Thanks.

Jon

Re: Bass project for my kid



"Jon Yaeger" <jono_1@bellsouth . net > wrote in message
news:C41D6945.B9B79%jono_1@bellsouth . net ...
> I've got an 11 year old who is interested in playing the bass guitar.
>
> I bought him a used Peavy KB 60 keyboard amp to get started and to see if
> it
> was what he wanted to do. It is.
>
> Problem is, the amp is too heavy to drag to a buddy's house for jamming,
> so
> I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
> that
> I can mate with a 10 inch speaker. The amp has a pair of EL84s in
> push-pull
> with an ultralinear OPT - for 14 watts RMS.
>
> The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
> Would
> I be right in assuming that the -3 dB point ought to be low enough for
> bass
> amp use?
>
> The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
> better off with an SPL of 93?
>
> I found a schematic for a Gibson GA-14 that looks just about perfect.
>
> Any thoughts suggestions?


Morning Jon, I don't have a lot of experience of building bass guitar
amps, but I share a workshop with two guys who build professionally.
They offer you the following tips:

The lowest fundamental on the bass guitar is E at 41Hz. Despite this
many guitar speakers have a 3dB point at 60Hz. Eminence, Celestion
and Fane are their three speakers of choice. They all have high sensitivity
- the Celestion for example is 100dB/W/m. Infinite baffle is a good choice
for the speaker enclosure.

A hi-fi amp is good for bass guitar, but a hi-fi speaker definitely is *not*

The OPT should be a substantial one.

6L6, 6550 and KT88s are often stipulated as tubes of choice.
Neither the EL84 or EL34 is liked (overbrittle sound, it seems)

In the tone stack, the Baxendal (aka James) circuit is preferred
by most builders, as it can be set to have a flat response.

Sensitivity can be about 50mV. Lowish Zo is desirable. 10-12dB
of NFB is commonly used.

My 2cents. Hope it is of use to you.
Cordially,

Iain

Re: Bass project for my kid

in article _u%Jj.321835$re4.67213@reader1.news.saunalahti.fi, Iain Churches
at IainNG@kolumbus.fi wrote on 4/6/08 4:04 AM:

>
>
> "Jon Yaeger" <jono_1@bellsouth . net > wrote in message
> news:C41D6945.B9B79%jono_1@bellsouth . net ...
>> I've got an 11 year old who is interested in playing the bass guitar.
>>
>> I bought him a used Peavy KB 60 keyboard amp to get started and to see if
>> it
>> was what he wanted to do. It is.
>>
>> Problem is, the amp is too heavy to drag to a buddy's house for jamming,
>> so
>> I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
>> that
>> I can mate with a 10 inch speaker. The amp has a pair of EL84s in
>> push-pull
>> with an ultralinear OPT - for 14 watts RMS.
>>
>> The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
>> Would
>> I be right in assuming that the -3 dB point ought to be low enough for
>> bass
>> amp use?
>>
>> The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
>> better off with an SPL of 93?
>>
>> I found a schematic for a Gibson GA-14 that looks just about perfect.
>>
>> Any thoughts suggestions?
>
>
> Morning Jon, I don't have a lot of experience of building bass guitar
> amps, but I share a workshop with two guys who build professionally.
> They offer you the following tips:
>
> The lowest fundamental on the bass guitar is E at 41Hz. Despite this
> many guitar speakers have a 3dB point at 60Hz. Eminence, Celestion
> and Fane are their three speakers of choice. They all have high sensitivity
> - the Celestion for example is 100dB/W/m. Infinite baffle is a good choice
> for the speaker enclosure.
>
> A hi-fi amp is good for bass guitar, but a hi-fi speaker definitely is *not*
>
> The OPT should be a substantial one.
>
> 6L6, 6550 and KT88s are often stipulated as tubes of choice.
> Neither the EL84 or EL34 is liked (overbrittle sound, it seems)
>
> In the tone stack, the Baxendal (aka James) circuit is preferred
> by most builders, as it can be set to have a flat response.
>
> Sensitivity can be about 50mV. Lowish Zo is desirable. 10-12dB
> of NFB is commonly used.
>
> My 2cents. Hope it is of use to you.
> Cordially,
>
> Iain
>
>



Thanks, Iain.

You've provided a lot of useful information. I'll guess it's back to Audio
Lab to find a better matched speaker.

My little guy is just wanting the amp for practice - he ain't ready to fill
up an arena quite yet. Portability is really important. Otherwise, I'd use
a phatter tube like the 6L6 or 6550.

There is an ulterior motive at play here . . . It's about coming up with a
good father / son project . . .

Cheers,

Jon

Re: Bass project for my kid

In article <_u%Jj.321835$re4.67213@reader1.news.saunalahti.fi>,
"Iain Churches" <IainNG@kolumbus.fi> wrote:

>
> In the tone stack, the Baxendal (aka James) circuit is preferred
> by most builders, as it can be set to have a flat response.

I'm still would like to see a reference that shows Baxendal had anything
to do with the James tone control circuit?


Regards,

John Byrns

--
Surf my web pages at, * fmamradios . com /

Re: Bass project for my kid

On Apr 6, 10:47 am, John Byrns <byr...@sbcglobal . net > wrote:
> In article < u%Jj.321835$re4.67...@reader1.news.saunalahti.fi>,
>  "Iain Churches" <Iai...@kolumbus.fi> wrote:
>
>
>
> > In the tone stack, the Baxendal (aka James) circuit is preferred
> > by most builders, as it can be set to have a flat response.
>
> I'm still would like to see a reference that shows Baxendal had anything
> to do with the James tone control circuit?
>
> Regards,
>
> John Byrns
>
> --
> Surf my web pages at,   * fmamradios . com /

He refers to James in his 1952 WW article on passive tone controls.

* home . com cast . net /~stphkeri/NegativeFeedbackTone.pdf

* home . com cast . net /~stphkeri/James SimpleToneControl.pdf

Is the "James" article from WW 1949.

I expect that the difference is that Baxendall used negative feedback,
but started from the James circuit. So, a perhaps a more proper
designation would be the James Circuit as modified by Baxendall?

But the descriptive "James-Baxendall" seems to be quite common.

Peter Wieck
Melrose Park, PA

Re: Bass project for my kid

In article
<af123b24-b2e9-40fe-ad6c-d54150bbb566@b64g2000hsa.googlegroups . com >,
Peter Wieck <pfjw@aol . com > wrote:

> On Apr 6, 10:47 am, John Byrns <byr...@sbcglobal . net > wrote:
> > In article < u%Jj.321835$re4.67...@reader1.news.saunalahti.fi>,
> >  "Iain Churches" <Iai...@kolumbus.fi> wrote:
> >
> > > In the tone stack, the Baxendal (aka James) circuit is preferred
> > > by most builders, as it can be set to have a flat response.
> >
> > I'm still would like to see a reference that shows Baxendal had anything
> > to do with the James tone control circuit?
> >
>
> He refers to James in his 1952 WW article on passive tone controls.
>
> * home . com cast . net /~stphkeri/NegativeFeedbackTone.pdf
>
> * home . com cast . net /~stphkeri/James SimpleToneControl.pdf
>
> Is the "James" article from WW 1949.
>
> I expect that the difference is that Baxendall used negative feedback,
> but started from the James circuit. So, a perhaps a more proper
> designation would be the James Circuit as modified by Baxendall?
>
> But the descriptive "James-Baxendall" seems to be quite common.

Thanks for the links, although I think I may have the original Wireless
World Baxendall article in my wireless World collection, and I have seen
the pdf of the James article before.

By the way your newsreader is still converting the "_" character in file
names to a space in the links.

At any rate, the question I am asking is where is the proof that
Baxendall was the actual inventor of the circuit known as the "James"
tone control circuit? I ask because many people in this goup have made
the outright claim that Baxendall was the true inventor of the "James"
tone control circuit, but no one has yet delivered any proof indicating
that was actually the case. Iain's post that I was responding to seems
to be again suggesting that the "James" circuit was actually
Baxendall's, although without making an outright claim to that effect, I
would like to see some evidence to back this notion up.


Regards,

John Byrns

--
Surf my web pages at, * fmamradios . com /

Re: Bass project for my kid

On Apr 7, 4:59 pm, John Byrns <byr...@sbcglobal . net > wrote:
> In article
> <af123b24-b2e9-40fe-ad6c-d54150bbb...@b64g2000hsa.googlegroups . com >,
>  Peter Wieck <p...@aol . com > wrote:
>
>
>
>
>
> > On Apr 6, 10:47 am, John Byrns <byr...@sbcglobal . net > wrote:
> > > In article < u%Jj.321835$re4.67...@reader1.news.saunalahti.fi>,
> > >  "Iain Churches" <Iai...@kolumbus.fi> wrote:
>
> > > > In the tone stack, the Baxendal (aka James) circuit is preferred
> > > > by most builders, as it can be set to have a flat response.
>
> > > I'm still would like to see a reference that shows Baxendal had anythi=
ng
> > > to do with the James tone control circuit?
>
> > He refers to James in his 1952 WW article on passive tone controls.
>
> > * home . com cast . net /~stphkeri/NegativeFeedbackTone.pdf
>
> > * home . com cast . net /~stphkeri/JamesSimpleToneControl.pdf
>
> > Is the "James" article from WW 1949.
>
> > I expect that the difference is that Baxendall used negative feedback,
> > but started from the James circuit. So, a perhaps a more proper
> > designation would be the James Circuit as modified by Baxendall?
>
> > But the descriptive "James-Baxendall" seems to be quite common.
>
> Thanks for the links, although I think I may have the original Wireless
> World Baxendall article in my wireless World collection, and I have seen
> the pdf of the James article before.
>
> By the way your newsreader is still converting the " " character in file
> names to a space in the links.
>
> At any rate, the question I am asking is where is the proof that
> Baxendall was the actual inventor of the circuit known as the "James"
> tone control circuit?  I ask because many people in this goup have made
> the outright claim that Baxendall was the true inventor of the "James"
> tone control circuit, but no one has yet delivered any proof indicating
> that was actually the case.  Iain's post that I was responding to seems
> to be again suggesting that the "James" circuit was actually
> Baxendall's, although without making an outright claim to that effect, I
> would like to see some evidence to back this notion up.
>
> Regards,
>
> John Byrns
>
> --
> Surf my web pages at,   * fmamradios . com /- Hide quoted text -
>
> - Show quoted text -

John:

I think that Baxendall would be the first to state that he merely
modified the James Circuit with the addition of feedback vs. inventing
it altogether.

Of course, that would depend on what one means by "invent". Edison
first described how tubes work - more-or-less, DeForest made a
practical tube, more-or-less, but between/during/before/after either
was much other work (from Fleming amongst others) without which it is
doubtful that much would have happened were it only Edison.

I think that as with much of these things, progress is incremental vs.
new first-principles. James was first in this case. That about sums it
up.

As to the "translation", your reader seems to be the only one having
this problem. I have one at work and a different one at home, neither
seems to have the issue.

Peter Wieck
Melrose Park, PA

Re: Bass project for my kid

In article
<27c33ef6-d398-48fa-80c3-96647f6afb2e@u3g2000hsc.googlegroups . com >,
Peter Wieck <pfjw@aol . com > wrote:

> On Apr 7, 4:59 pm, John Byrns <byr...@sbcglobal . net > wrote:
> > In article
> > <af123b24-b2e9-40fe-ad6c-d54150bbb...@b64g2000hsa.googlegroups . com >,
> >  Peter Wieck <p...@aol . com > wrote:
> >
> > > On Apr 6, 10:47 am, John Byrns <byr...@sbcglobal . net > wrote:
> > > > In article < u%Jj.321835$re4.67...@reader1.news.saunalahti.fi>,
> > > >  "Iain Churches" <Iai...@kolumbus.fi> wrote:
> >
> > > > > In the tone stack, the Baxendal (aka James) circuit is preferred
> > > > > by most builders, as it can be set to have a flat response.
> >
> > > > I'm still would like to see a reference that shows Baxendal had anything
> > > > to do with the James tone control circuit?
> >
> > > He refers to James in his 1952 WW article on passive tone controls.
> >
> > > * home . com cast . net /~stphkeri/NegativeFeedbackTone.pdf
> >
> > > * home . com cast . net /~stphkeri/JamesSimpleToneControl.pdf
> >
> > > Is the "James" article from WW 1949.
> >
> > > I expect that the difference is that Baxendall used negative feedback,
> > > but started from the James circuit. So, a perhaps a more proper
> > > designation would be the James Circuit as modified by Baxendall?
> >
> > > But the descriptive "James-Baxendall" seems to be quite common.
> >
> > Thanks for the links, although I think I may have the original Wireless
> > World Baxendall article in my wireless World collection, and I have seen
> > the pdf of the James article before.
> >
> > By the way your newsreader is still converting the "_" character in file
> > names to a space in the links.
> >
> > At any rate, the question I am asking is where is the proof that
> > Baxendall was the actual inventor of the circuit known as the "James"
> > tone control circuit?  I ask because many people in this goup have made
> > the outright claim that Baxendall was the true inventor of the "James"
> > tone control circuit, but no one has yet delivered any proof indicating
> > that was actually the case.  Iain's post that I was responding to seems
> > to be again suggesting that the "James" circuit was actually
> > Baxendall's, although without making an outright claim to that effect, I
> > would like to see some evidence to back this notion up.
> >
>
> John:
>
> I think that Baxendall would be the first to state that he merely
> modified the James Circuit with the addition of feedback vs. inventing
> it altogether.
>
> Of course, that would depend on what one means by "invent". Edison
> first described how tubes work - more-or-less, DeForest made a
> practical tube, more-or-less, but between/during/before/after either
> was much other work (from Fleming amongst others) without which it is
> doubtful that much would have happened were it only Edison.
>
> I think that as with much of these things, progress is incremental vs.
> new first-principles. James was first in this case. That about sums it
> up.

It may sum it up as far as you are concerned, and it pretty well does as
far as I am concerned, but somehow I don't think it is enough to
convince the Baxendall true believers, so I am still left wondering are
they right, or am I right?

> As to the "translation", your reader seems to be the only one having
> this problem. I have one at work and a different one at home, neither
> seems to have the issue.

Please extend my apology to your newsreader software as it seems I have
wrongly accused it, and the fault is with my software in a very
mysterious way.

When I had this trouble with a link you had posted before, I thought I
had vindicated my software and determined that the trouble must be at
your end. This morning when I read your post I decided that maybe there
was some kind of setting or preference that I had messed up which
instructed my newsreader to convert underscores to spaces. I was in no
mood to search through dozens of preferences to see if such a one even
exists. However I have two computers although I don't use the other one
for reading newsgroups, but coincidentally just a couple of days ago I
installed the newsreader program I use on it, a newer version at that,
so I thought I would see what it did with your underscores, and sure
enough they came through perfectly. I thought great there must be a bug
in the older version of the newsreader I was using, so it would be an
easy fix to just upgrade the newsreader on this computer, so I did just
that, even though I was left wondering why I had thought I had earlier
proved to my satisfaction that it was not my news reader.

At this point things became very confusing. There are three basic parts
to the newsreader that I am aware of, first is the newsreader
application program itself, second is a settings or preferences file,
and third is groups list file, or files. What I call the groups file
apparently contains a list of groups that have been subscribed to, as
well as information about which posts have already been read and which
haven't been read. By pure coincidence I started up the new newsreader
program by clicking directly on the program file rather than on an
existing groups file, this starts the newsreader without a list of
subscribed groups, so the first thing I did was subscribe to
rec.audio.tubes and call up your post, sure enough the underscore came
through perfectly just as on my other computer, no surprise there.

But then things started getting interesting, I went back to the groups
file with my full group list expecting that I had solved the problem,
however when I looked at your post the problem was back, and I was
mystified as to what the groups file might contain that would cause this
effect, as the same settings/preferences file was used in either case.
That is the point I left it this morning.

During the day my subconscious has come up with a possible explanation
of why I thought I had proved it was your newsreader, I suspect that I
had used another group, maybe rec.antiques.radio+phono to test at that
time, and I suspect that the problem is associated with a particular
group, rec.audio.tubes, in a particular groups file. I can't imagine
what might be in the groups file that could affect the newsreader in
this way, perhaps I will have to read the instruction manual to see if
it gives a hint of what is stored in the groups file other than the
obvious, and maybe contact the author. Once I send this post I will
also test to see if unsubscribing from rec.audio.tubes, and then
re-subscribing will fix the problem, or if I have to create a new groups
file, which I know will fix the problem.

Again, sorry for accusing your newsreader software.


Regards,

John Byrns

--
Surf my web pages at, * fmamradios . com /

Re: Bass project for my kid



"John Byrns" <byrnsj@sbcglobal . net > wrote in message
news:byrnsj-77B3FB.15595707042008@newsclstr03.news.prodigy . net ...
> In article
> <af123b24-b2e9-40fe-ad6c-d54150bbb566@b64g2000hsa.googlegroups . com >,
> Peter Wieck <pfjw@aol . com > wrote:
>
>> On Apr 6, 10:47 am, John Byrns <byr...@sbcglobal . net > wrote:
>> > In article < u%Jj.321835$re4.67...@reader1.news.saunalahti.fi>,
>> > "Iain Churches" <Iai...@kolumbus.fi> wrote:
>> >
>> > > In the tone stack, the Baxendal (aka James) circuit is preferred
>> > > by most builders, as it can be set to have a flat response.
>> >
>> > I'm still would like to see a reference that shows Baxendal had
>> > anything
>> > to do with the James tone control circuit?
>> >
>>
>> He refers to James in his 1952 WW article on passive tone controls.
>>
>> * home . com cast . net /~stphkeri/NegativeFeedbackTone.pdf
>>
>> * home . com cast . net /~stphkeri/James SimpleToneControl.pdf
>>
>> Is the "James" article from WW 1949.
>>
>> I expect that the difference is that Baxendall used negative feedback,
>> but started from the James circuit. So, a perhaps a more proper
>> designation would be the James Circuit as modified by Baxendall?
>>
>> But the descriptive "James-Baxendall" seems to be quite common.
>
> Thanks for the links, although I think I may have the original Wireless
> World Baxendall article in my wireless World collection, and I have seen
> the pdf of the James article before.
>
> By the way your newsreader is still converting the "_" character in file
> names to a space in the links.
>
> At any rate, the question I am asking is where is the proof that
> Baxendall was the actual inventor of the circuit known as the "James"
> tone control circuit? I ask because many people in this goup have made
> the outright claim that Baxendall was the true inventor of the "James"
> tone control circuit, but no one has yet delivered any proof indicating
> that was actually the case. Iain's post that I was responding to seems
> to be again suggesting that the "James" circuit was actually
> Baxendall's, although without making an outright claim to that effect, I
> would like to see some evidence to back this notion up.
>

John. I think the fact that Baxandall gives credit to James
in his article helps to clarify this "chicken and egg" situation. It seems
that Peter Baxandall used the same idea for his feedback topology.

In fact these are two separate circuits, but as you say, they are
commonly given the generic name "Baxandall" I am told that
in guitar amps, the tone stack is often called "James" even
though the feedback version may be used. Curious.

Regards
Iain

Re: Bass project for my kid


"Jon Yaeger" <jono_1@bellsouth . net > wrote in message
news:C41D6945.B9B79%jono_1@bellsouth . net ...
> I've got an 11 year old who is interested in playing the bass guitar.
>
> I bought him a used Peavy KB 60 keyboard amp to get started and to see if
it
> was what he wanted to do. It is.
>
> Problem is, the amp is too heavy to drag to a buddy's house for jamming,
so
> I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
that
> I can mate with a 10 inch speaker. The amp has a pair of EL84s in
push-pull
> with an ultralinear OPT - for 14 watts RMS.
>
> The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
Would
> I be right in assuming that the -3 dB point ought to be low enough for
bass
> amp use?
>
> The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
> better off with an SPL of 93?
>
> I found a schematic for a Gibson GA-14 that looks just about perfect.
>
> Any thoughts suggestions?
>
> Thanks.
>
> Jon
>


Help him drag the big amplifier over to his buddy's house...than have him
leave it there!
He can turn it up to full volume!

He can use the small amp at home, after you have adjusted the output to a
sane and sensible one watt!

<G> !!!!! <G>

Re: Bass project for my kid

In article <C41D6945.B9B79%jono_1@bellsouth . net >, Jon Yaeger <jono_1@bellsouth . net > wrote:
>I've got an 11 year old who is interested in playing the bass guitar.
>
>I bought him a used Peavy KB 60 keyboard amp to get started and to see if it
>was what he wanted to do. It is.
>
>Problem is, the amp is too heavy to drag to a buddy's house for jamming, so
>I looked around my shelf and found a Heathkit EA-3 mono tube amplifier that
>I can mate with a 10 inch speaker. The amp has a pair of EL84s in push-pull
>with an ultralinear OPT - for 14 watts RMS.
>
>The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB. Would
>I be right in assuming that the -3 dB point ought to be low enough for bass
>amp use?
>
>The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
>better off with an SPL of 93?
>
>I found a schematic for a Gibson GA-14 that looks just about perfect.
>
>Any thoughts suggestions?

Its likely the 86 dB will have lower bass. Most bass amps need a 15 or larger to
get decent fundamental bass notes as well as proper box matching. There
has only been one use of a 10 inch and that has been well documented.
I don't know if the driver is available. Do a search on Len Moskowitz 10 inch
bass.

greg

Re: Bass project for my kid



"GregS" <zekfrivo@zekfrivolous . com > wrote in message
news:ftd52m$pu5$1@usenet01.srv.cis.pitt.edu...
> In article <C41D6945.B9B79%jono_1@bellsouth . net >, Jon Yaeger
> <jono_1@bellsouth . net > wrote:
>>I've got an 11 year old who is interested in playing the bass guitar.
>>
>>I bought him a used Peavy KB 60 keyboard amp to get started and to see if
>>it
>>was what he wanted to do. It is.
>>
>>Problem is, the amp is too heavy to drag to a buddy's house for jamming,
>>so
>>I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
>>that
>>I can mate with a 10 inch speaker. The amp has a pair of EL84s in
>>push-pull
>>with an ultralinear OPT - for 14 watts RMS.
>>
>>The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
>>Would
>>I be right in assuming that the -3 dB point ought to be low enough for
>>bass
>>amp use?
>>
>>The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
>>better off with an SPL of 93?
>>
>>I found a schematic for a Gibson GA-14 that looks just about perfect.
>>
>>Any thoughts suggestions?
>
> Its likely the 86 dB will have lower bass. Most bass amps need a 15 or
> larger to
> get decent fundamental bass notes as well as proper box matching. There
> has only been one use of a 10 inch and that has been well documented.
> I don't know if the driver is available. Do a search on Len Moskowitz 10
> inch
> bass.
>

Hi Greg I am told by a guy who builds guitar amps
professionally that a bass rehearsal amp (as this is)
does not need a 15 inch speaker, particularly as
portability is a priority. The fundamental of the low
E is not too important. The 2H convinces the brain
that the fundamental is there, good and strong

Regards
Iain

Re: Bass project for my kid

In article <vTrKj.322684$Bd5.221704@reader1.news.saunalahti.fi>, "Iain Churches" <IainNG@kolumbus.fi> wrote:
>
>
>"GregS" <zekfrivo@zekfrivolous . com > wrote in message
>news:ftd52m$pu5$1@usenet01.srv.cis.pitt.edu...
>> In article <C41D6945.B9B79%jono_1@bellsouth . net >, Jon Yaeger
>> <jono_1@bellsouth . net > wrote:
>>>I've got an 11 year old who is interested in playing the bass guitar.
>>>
>>>I bought him a used Peavy KB 60 keyboard amp to get started and to see if
>>>it
>>>was what he wanted to do. It is.
>>>
>>>Problem is, the amp is too heavy to drag to a buddy's house for jamming,
>>>so
>>>I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
>>>that
>>>I can mate with a 10 inch speaker. The amp has a pair of EL84s in
>>>push-pull
>>>with an ultralinear OPT - for 14 watts RMS.
>>>
>>>The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
>>>Would
>>>I be right in assuming that the -3 dB point ought to be low enough for
>>>bass
>>>amp use?
>>>
>>>The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
>>>better off with an SPL of 93?
>>>
>>>I found a schematic for a Gibson GA-14 that looks just about perfect.
>>>
>>>Any thoughts suggestions?
>>
>> Its likely the 86 dB will have lower bass. Most bass amps need a 15 or
>> larger to
>> get decent fundamental bass notes as well as proper box matching. There
>> has only been one use of a 10 inch and that has been well documented.
>> I don't know if the driver is available. Do a search on Len Moskowitz 10
>> inch
>> bass.
>>
>
>Hi Greg I am told by a guy who builds guitar amps
>professionally that a bass rehearsal amp (as this is)
>does not need a 15 inch speaker, particularly as
>portability is a priority. The fundamental of the low
>E is not too important. The 2H convinces the brain
>that the fundamental is there, good and strong

Most try to do it like that. Next thing you know they are using
the small portable ones for the real deal. I just have too many gripes
with bands who are not doing it right. All I know is you got to feel the bass
most of the time with live music. Its usually that black bass player that has the right
equipment.

greg

Re: Bass project for my kid



"GregS" <zekfrivo@zekfrivolous . com > wrote in message
news:ftdj1s$5$1@usenet01.srv.cis.pitt.edu...
> In article <vTrKj.322684$Bd5.221704@reader1.news.saunalahti.fi>, "Iain
> Churches" <IainNG@kolumbus.fi> wrote:
>>
>>
>>"GregS" <zekfrivo@zekfrivolous . com > wrote in message
>>news:ftd52m$pu5$1@usenet01.srv.cis.pitt.edu...
>>> In article <C41D6945.B9B79%jono_1@bellsouth . net >, Jon Yaeger
>>> <jono_1@bellsouth . net > wrote:
>>>>I've got an 11 year old who is interested in playing the bass guitar.
>>>>
>>>>I bought him a used Peavy KB 60 keyboard amp to get started and to see
>>>>if
>>>>it
>>>>was what he wanted to do. It is.
>>>>
>>>>Problem is, the amp is too heavy to drag to a buddy's house for jamming,
>>>>so
>>>>I looked around my shelf and found a Heathkit EA-3 mono tube amplifier
>>>>that
>>>>I can mate with a 10 inch speaker. The amp has a pair of EL84s in
>>>>push-pull
>>>>with an ultralinear OPT - for 14 watts RMS.
>>>>
>>>>The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB.
>>>>Would
>>>>I be right in assuming that the -3 dB point ought to be low enough for
>>>>bass
>>>>amp use?
>>>>
>>>>The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
>>>>better off with an SPL of 93?
>>>>
>>>>I found a schematic for a Gibson GA-14 that looks just about perfect.
>>>>
>>>>Any thoughts suggestions?
>>>
>>> Its likely the 86 dB will have lower bass. Most bass amps need a 15 or
>>> larger to
>>> get decent fundamental bass notes as well as proper box matching. There
>>> has only been one use of a 10 inch and that has been well documented.
>>> I don't know if the driver is available. Do a search on Len Moskowitz 10
>>> inch
>>> bass.
>>>
>>
>>Hi Greg I am told by a guy who builds guitar amps
>>professionally that a bass rehearsal amp (as this is)
>>does not need a 15 inch speaker, particularly as
>>portability is a priority. The fundamental of the low
>>E is not too important. The 2H convinces the brain
>>that the fundamental is there, good and strong
>
> Most try to do it like that. Next thing you know they are using
> the small portable ones for the real deal. I just have too many gripes
> with bands who are not doing it right. All I know is you got to feel the
> bass
> most of the time with live music. Its usually that black bass player that
> has the right
> equipment.
>

The OP (Jon) was asking about a rehearsal amp for his
11 year old son. So he's a few years away from the real deal:-)
Probably the portability factor is high on the list (so that he
can go to jam with his mates) and so perhaps this should take
precedence over his being about to play the bottom E fundamental
<-1dB


Regards
Iain

Re: Bass project for my kid

in article C41D6945.B9B79%jono_1@bellsouth . net , Jon Yaeger at
jono_1@bellsouth . net wrote on 4/5/08 5:37 PM:

> I've got an 11 year old who is interested in playing the bass guitar.
>
> I bought him a used Peavy KB 60 keyboard amp to get started and to see if it
> was what he wanted to do. It is.
>
> Problem is, the amp is too heavy to drag to a buddy's house for jamming, so
> I looked around my shelf and found a Heathkit EA-3 mono tube amplifier that
> I can mate with a 10 inch speaker. The amp has a pair of EL84s in push-pull
> with an ultralinear OPT - for 14 watts RMS.
>
> The original power bandwidth of the amp is 30 Hz. - 20 Khz, +/1 1 dB. Would
> I be right in assuming that the -3 dB point ought to be low enough for bass
> amp use?
>
> The speaker I have has an SPL of 86 dB/W and I'm wondering if I am much
> better off with an SPL of 93?
>
> I found a schematic for a Gibson GA-14 that looks just about perfect.
>
> Any thoughts suggestions?
>
> Thanks.
>
> Jon
>


I cobbled together a composite schematic using the Heathkit EA-3 chassis,
power supply, and UL output section and the front end and inverter/driver
from a Gibson GA-15 guitar amp.

Many thanks to Doug Bannard for his generous help with circuit analysis and
advice.

The schematic is posted at: w w w .yaegeraudio . com /bass_amp.pdf

I bought a speaker more suited to the project, a Goldwood GW-1058 which has
a range of 31 Hz. 4900 Hz. (still looking for the response curves) and an
output of 94dB 1W/1M.

Are grid stoppers a good idea for the 5751 and 6EU7?

Suggestions welcomed.

Jon