# Sylvania combo made in Dunnville



## Alan Small (Dec 30, 2019)

I picked up this cute 1959 record player amp, 2 x 6V6 and 1 x 12ax7, combo today...

Sounds great as is and all original including the tubes.





































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## Mark Brown (Jan 4, 2022)

I think cute about sums it up.

I like it!!


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## Latole (Aug 11, 2020)

Vey nice, keep the original look.
It just need a guitar jack in the back


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## Paul Running (Apr 12, 2020)

A rare find Alan...well done. She looks like a miniature console. I read that it is similar to model 971, minus the radio section. Have fun playing with it.


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## Always12AM (Sep 2, 2018)

It was well taken care of for 63 years and now it’s in the right hands!.


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## Alan Small (Dec 30, 2019)

Paul Running said:


> A rare find Alan...well done. She looks like a miniature console. I read that it is similar to model 971, minus the radio section. Have fun playing with it.
> View attachment 441677


Thank you for that schematic!


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## Alan Small (Dec 30, 2019)

A 12AU7 was in the 12AX7 slot so I installed a proper tube and swapped the rca in jack for 1/4"...has more volume and still silent when not playing which is a good thing..


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## nonreverb (Sep 19, 2006)

Find a decent preamp for it or make one and a way you go....


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## Alan Small (Dec 30, 2019)

The B+ on the 12ax7 is under 70 volts and at the cap can it is 186v.

I will assume for now that the load resistors have drifted and should be replaced to get the plate back up to the 130v range.

Will hear the difference and proceed from that point.


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## Paul Running (Apr 12, 2020)

Alan Small said:


> The B+ on the 12ax7 is under 70 volts and at the cap can it is 186v.
> 
> I will assume for now that the load resistors have drifted and should be replaced to get the plate back up to the 130v range.
> 
> Will hear the difference and proceed from that point.


What is the voltage at the junction of R18/C8A?


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## Alan Small (Dec 30, 2019)

Paul Running said:


> What is the voltage at the junction of R18/C8A?


314v


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## Paul Running (Apr 12, 2020)

Are both 12AX7's plates measuring lower than normal?


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## Alan Small (Dec 30, 2019)

Yes...input is 56v and phase is 70v

Maybe stereo design wants to be down there...I am fiddling to push it a bit and learn how each change sounds


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## Paul Running (Apr 12, 2020)

Sorry for interrupting you, Alan.


Alan Small said:


> Maybe stereo design wants to be down there.


You mean mono?


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## Paul Running (Apr 12, 2020)

Is this correct for the voltages in blue?


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## Alan Small (Dec 30, 2019)

Paul Running said:


> Sorry for interrupting you, Alan.
> 
> You mean mono?


Yes...for a record player signal is this design...i grabbed the wrong word


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## Alan Small (Dec 30, 2019)

Paul Running said:


> Is this correct for the voltages in blue?
> View attachment 441915


Yes


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## epis (Feb 25, 2012)

Very cool vintage amp, I would change R18 to not more than 22k, R9, 14, to 100k , these are more realistic values for the amp.
Low readings on preamp tubes anodes are most likely the tube 12ax7, but even 110v is to low for that tube.


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## Alan Small (Dec 30, 2019)

epis said:


> Very cool vintage amp, I would change R18 to not more than 22k, R9, 14, to 100k , these are more realistic values for the amp.
> Low readings on preamp tubes anodes are most likely the tube 12ax7, but even 110v is to low for that tube.


✅✅ I will report as I make each experiment


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## nonreverb (Sep 19, 2006)

You might want to add a bypass cap to the cathode resistor too. Start with a small value first to see what kind of gain change occurs and go from there. Going too big might make it a wee bit harsh though.


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## diyfabtone (Mar 9, 2016)

Great looking little amp with some history. Have fun!


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## Alan Small (Dec 30, 2019)

That is also in the plans and i will describe the audio results as i make each adjustment/change


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## faracaster (Mar 9, 2006)

I cannot add anything technical to the conversation. However, I LOVEEEE the look of that thing !!!!


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## Alan Small (Dec 30, 2019)

I replaced the blocking caps and gave it a go...after 15 minutes or so it lost its power somewhat...
So
I replaced the lytic cap can and voila lotsa everthing...very solid yet maybe a wee bit too edgy...

Next i changed out each resistor at a time and had a listen..a noticable improvement overall and the old resisitors were far off their colour coded bands...some double the resistance..

After all this i separated the cathodes in the 12ax7...input has 1.5k and a 100/100 bypass...pi has 1.5k meeting the voltage divider 1 meg and 56k borrowed from the 5e3.
220k(s) used for the plates of that 12ax7 (resulted in 125 ish operating volts).
Running very nicely with sensitivity to my fingers and the guitar controls...

A pleasurable servicing/hobby experience. The old parts are going to @Always12AM for his creative pedal builds.

The alnico speakers are passable but not dynamic...there is room for a nice 10" which the next owner may want to install and enjoy the bigger sound.

The tone stack(pre-tube input) is redundant(guitar already has volume and tone) and sucks some life out the signal; I have bypassed it completely which has livened it up pleasantly


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## Alan Small (Dec 30, 2019)

Further...

the original 6v6 common cathode resisitor was [email protected]
and i upped it to [email protected] plus added a 100/100 bypass cap across it.

added a 3 prong

lifted the 6.3 volt supply from the chassis and installed 100k s to imitate a centre tap heater system


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## Alan Small (Dec 30, 2019)

Also noted....it has no fuse unless it is hiding up behind the tone stack...
I will have a look and install one if i dont find it.
And...
The phono input to grid was a .047 cap(probably to block DC from the record player preamp- some.pedal friendly modern guitar amps have this to quiet the noise of pedals) which i replaced with a 22k resistor and 1 meg to ground


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## Paul Running (Apr 12, 2020)

Alan Small said:


> probably to block DC from the record player preamp


Did you change R7 out? V1A was operating mainly from grid-leak bias, a 6.8MΩ resistor...that's the main purpose of the blocking cap, to block DC from flowing back to the input.


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## Alan Small (Dec 30, 2019)

Paul Running said:


> Did you change R7 out? V1A was operating mainly from grid-leak bias, a 6.8MΩ resistor...that's the main purpose of the blocking cap, to block DC from flowing back to the input.


Yes, a 1 meg at the shunting input jack ala common fender/rca designs


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## Alan Small (Dec 30, 2019)

Here is a vid clip 









Quick Share


Expired




linksharing.samsungcloud.com


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## Alan Small (Dec 30, 2019)

Alan Small said:


> Yes, a 1 meg at the shunting input jack ala common fender/rca designs
> View attachment 442803


Is this a suitable place for it?

The "high fi" schematic world reminds me that simple guitar amp topology is like grade 3 compared to university


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## nonreverb (Sep 19, 2006)

Alan Small said:


> Here is a vid clip
> 
> 
> 
> ...


Nice work! Have you considered replacing the two-way speakers with something more conventional for guitar?


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## Alan Small (Dec 30, 2019)

The stock alnico speakers are sounding quite nice and @Always12AM has a weber alnico 8 sig guitar speaker that could be a drop in if needed..

A reminder that the Celestion Alnico Blue, considered the benchmark of great guitar speaker tone is, and began as, a radio speaker just like this one


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## Alan Small (Dec 30, 2019)

nonreverb said:


> Nice work! Have you considered replacing the two-way speakers with something more conventional for guitar?


You read my mind...i was typing as you posted the idea.


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## Alan Small (Dec 30, 2019)

Maybe a handle?


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## Paul Running (Apr 12, 2020)

Alan Small said:


> Is this a suitable place for it?


That's a practical place for it. Ideally components should be installed as close to the active device as possible...not always practical for the person servicing the gear.


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## Alan Small (Dec 30, 2019)

Paul Running said:


> That's a practical place for it. Ideally components should be installed as close to the active device as possible...not always practical for the person servicing the gear.


Gotcha. Thanks.
I have placed most parts right against the sockets in the past however it gets crowded🤪...I need to get my mark bartel on!


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## Always12AM (Sep 2, 2018)

I think you have done it Justice in keeping its orignal appearance and ensuring that it sounds like it did the day it left the factory!

Such a cool amp.


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## nonreverb (Sep 19, 2006)

Alan Small said:


> The stock alnico speakers are sounding quite nice and @Always12AM has a weber alnico 8 sig guitar speaker that could be a drop in if needed..
> 
> A reminder that the Celestion Alnico Blue, considered the benchmark of great guitar speaker tone is, and began as, a radio speaker just like this one
> View attachment 442846
> ...


A caveat if I may...The speakers' power handling will be significantly less than when new. Old dry paper, spiders, rims and glues can conspire against you. Take it from someone whose slinky'd a couple.


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## Alan Small (Dec 30, 2019)

Always12AM said:


> I think you have done it Justice in keeping its orignal appearance and ensuring that it sounds like it did the day it left the factory!
> 
> Such a cool amp.


I started by simply servicing it: cleaning all contacts and listening.
It was original and working at that point which was not ideally a guitar amp nor was it operating at its fullest potential as any kind of amp; the cap can had the dc from the rectifier charging only one of four 20uf cells and the resistor feeding the second, third and fourth cells was open(meaning the other cells were receiving a charge through the dielectric itself and not through a wire!) which is a sure sign of part failure.
After changing that and then altering the units input design and modifying the pi took the amp in a non original direction...sounds great with guitar as a powerful champ might and plays music from my cell phone through an adaptor adequately.

A fun project that is ready for enjoyment by someone who plays guitar at home for pleasure and recording or quiet gigs.


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## Alan Small (Dec 30, 2019)

nonreverb said:


> A caveat if I may...The speakers' power handling will be significantly less than when new. Old dry paper, spiders, rims and glues can conspire against you. Take it from someone whose slinky'd a couple.


A weber AlNiCo SiG 8" os waiting in the wings if needed....so far no notes(literally) of speaker stress are manifesting.

Another old guy, who rebuilt speakers somewhere in scarborough for many years, told me he often would use a product called BARGE to paint old dried up guitar speaker cones and surrounds; he also used dollar store goop called PUZZLE SAVER which he said was almost as good as BARGE and handy for anyone wanting to give new life to speakers that surely will disintegrate otherwise.







,


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## Paul Running (Apr 12, 2020)

I used to experiment with a watered down solution of Elmer's white glue, basically similar to the puzzle saver.


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## Alan Small (Dec 30, 2019)

A WGS Veteran 10" is being mounted today in place of the tired 8" which was a little thin sounding last eve at a trio gig










10" Veteran - 20 Watts | Warehouse Guitar Speakers



thank you @Always12AM for the wgs and crossover 4.7uf Janzten(for the 4")


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## Alan Small (Dec 30, 2019)

a fellow member has adopted this amp and I will make a delivery to its new home in Scarborough in the next week: the amp will be thoroughly tested and enjoyed with a trio of Yanuziello s


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## epis (Feb 25, 2012)

IMHO, that amp is missing one triode gain stage in preamp to be a guitar amp.
Did you try it with some kind of booster pedal in front ?


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## Alan Small (Dec 30, 2019)

epis said:


> IMHO, that amp is missing one triode gain stage in preamp to be a guitar amp.
> Did you try it with some kind of booster pedal in front ?


Thanks: an extra triode is not in the plans to achieve the audio performance I hoped for in this project; consider a champ or princeton as a suitable guitar amp without an extra triode...they(fender) sold a few of them

On another project I will consider an extra triode stage if it suits the desired outcome.


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## Alan Small (Dec 30, 2019)

The WGS seemed a bit thinner sounding compared to my test cab(which is a 12" red, white and blues) and I tried a lil buddy for a test and the lows were more than needed for clear clean playing and the WGS is going back in😊
The vintage back panel will hide the modern appearance.


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## Mark Brown (Jan 4, 2022)

Alan Small said:


> View attachment 443187


The speaker is so very, very out of place even if I can appreciate why it is there. Nice work man.


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## Alan Small (Dec 30, 2019)

a proper fuse has been installed on the hot lead


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## faracaster (Mar 9, 2006)

Alan Small said:


> a fellow member has adopted this amp and I will make a delivery to its new home in Scarborough in the next week: the amp will be thoroughly tested and enjoyed with a trio of Yanuziello s


Had a delightful morning with Alan...the Dunville Horror ...and the Trio de Yanuziello . 
This amp has way more fidelity than I was expecting. I'm very happy. 
Also.....fits my man-cave to a T !!!


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## Mark Brown (Jan 4, 2022)

Looks like it found its home. That really works in there my man. 

Also I have to say this is the first time I realized how big it actually is.


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