Snider Prototype (Traynor YGM-4)

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tictac
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Re: Snider Prototype (Traynor YGM-4)

Post by tictac »

Reverb input is wrong on the schematic.....

TT
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

tictac wrote: Tue Apr 11, 2017 8:25 pm Reverb input is wrong on the schematic.....

TT
I see that. I'll be fully updating the schematic soon....

PT is labeled HT-6080 (9960214) and OT is labeled HT-6074 (9960209). Are these Hammond codes?
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10thTx
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Re: Snider Prototype (Traynor YGM-4)

Post by 10thTx »

Any update on the schematic?

With respect, 10thtx
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

10thTx wrote: Fri Apr 14, 2017 1:27 am Any update on the schematic?

With respect, 10thtx
I plan to get to it soon, but just buried with other things this week. If you feel like taking another pass, be my guest because it will probably have to wait until after the weekend for me.
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

Here is an updated schematic. I'll be reviewing some more.

EDIT: PLEASE SEE FIRST POST IN THREAD FOR LATEST SCHEMATIC
Last edited by sonicmojo on Sun May 07, 2017 5:38 pm, edited 2 times in total.
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Bryan
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

I'm making my own variation of this circuit with switchable tube/SS rectification into an Ampeg B-100 combo donor. Her's my board layout.
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Bryan
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

More progress.
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joeboo88
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Re: Snider Prototype (Traynor YGM-4)

Post by joeboo88 »

Looking good. I was gonna start mine, but my mini bassman kit arrived from RJ so that's first.
Keep going....
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

joeboo88 wrote: Thu Apr 27, 2017 2:30 am Looking good. I was gonna start mine, but my mini bassman kit arrived from RJ so that's first.
Keep going....
Cool. I'm glad you're going to try it too. The original Snider amp is just a loaner to me so I have to give it back at some point - thus I am motivated to build my own version. I've never heard a production California or Chicago but there are some good reviews. I decided to build this one with EL84s like the original. I'm not entirely happy with the donor amp that I picked but it had the right number of pot holes in it and the steel is not too bad for drilling extra holes. I'll have to figure out a way to mount it well in the cab as it was front load and doesn't have a good set of brackets to mount it. I went to town on the closed back cab with a saw and will probably put a 12" speaker in it. It will be a compact little combo when all said and done. Hopefully it will sound okay!

Wiring the board now. I'll probably have it done this weekend and then figure out a faceplate or labels.
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

I always like this part of building an amp. It's a big mess at this point but comes into shape bit by bit......I went with stranded teflon this time and it makes the job a bit quicker since shrink wrap is not really needed. I'm undecided on heater wiring positioning. I usually elevate and it may be better this time with the reverb jacks as I have positioned them now being in the way. It's not going to be as tidy as some builds I have done but I wanted all the wiring to be accessible on top so I can be sure of all connections. I've had some under board jumpers fall out before.....which can be painful to figure out.
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didit
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Re: Snider Prototype (Traynor YGM-4)

Post by didit »

Progress, excellent. Curious regarding transformer choices.

Best .. Ian
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

didit wrote: Mon May 01, 2017 4:14 pm Progress, excellent. Curious regarding transformer choices.

Best .. Ian
I went with Hammond 270DX and P-T1750H (20W) and a 4H choke.

I'm almost finished wiring. Just on the power switching now and heater wires last.

I went with a single star ground for the preamp and single star ground for the power section. The gain pot is grounded per the original layout so I may change that up if I get any hum.
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

Fired it up and everything works! Ran out of time today to figure out the significant 60hz hum that is present. If I tack a 100uf filter cap onto the 20uF first filter, the hum goes away. I wonder if my 4H choke is undersized for this circuit? I never measured the one in the Snider but it is very big. Either that or the new CE can cap I put in it has a fault......
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sonicmojo
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Re: Snider Prototype (Traynor YGM-4)

Post by sonicmojo »

Here's a pic of the completed amp. It is pretty much wild sounding just like the original. B+ is lower - around 350 for SS and 332 for tube rectified as opposed to the near 400V for the original but I have smaller PT.

It seems to need more filtering than the initial can cap 20uF can do. Tacking a 100uF into the circuit on top of that fixed the 60Hz hum. I don't like the solution but seems to be necessary. I tried a 20uF axial cap in place of the can cap node and that didn't solve it either so the can cap is okay I think.

I've also had 120Hz hum issues and mostly resolved them with moving some of my ground points around. The hum is now minimal but still there. The amp is dead quiet when I remove the PI tube, but removing all three other preamp tubes doesn't change anything. If I turn down the PPIMV master volume, the hum goes away completely. Turning other knobs does not affect the hum level so I am suspecting a remaining ground loop issue. Maybe I should install a buss bar and ground right next to the input jack. Right now I have preamp star grounded center of the chassis in front and the input jack is grounded to the chassis. There is a big cutout in the donor chassis near the front that I patched with an aluminum plate and that probably doesn't help ground loop issues.

I also get a momentary squeal when I turn standby "ON". It doesn't occur when I just power off though. Not sure why that is happening. I've tried moving some wires around near the choke but it didn't help.

Certain tubes in V1 can induce squealing or motor boating when gain is turned way up. I have this same issue with the original Snider so I guess it has to do with the circuit. Just have to watch what tube to put there.

If anyone has any thoughts, please let me know. I'd especially like to eliminate the remaining ground loop issue. At least that is what I think it is......


Thanks!
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didit
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Re: Snider Prototype (Traynor YGM-4)

Post by didit »

No thoughts on ground loop. Look into original choke. Based on physical dimensions & DC resistance you'll get good sense. Inductance is filtering.

Best .. Ian
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