Conversion request

[rzenc]

Hi Folks,
So my friend requested me to convert his Laney GH100L to a JCM 800 2203. Both amps have almost the same controls, i.e. volume - treble - mid - bass - master lovume - presence. Both amps uses the same number of output tubes -1xECC83 as P.I. and 4xEL34. JCM 800 2203 uses 2 preamp tubes, ECC83 whislt GH100L uses 3xECC83. So I believe the P.T. has enough juice to light tubes 
H.T. voltages are pretty much on the ball park.
Reservoir cap on both amps are 100uF, then follows a choke and  them things go different...
I was thinking about installing  a tube loopFX - I hate seeing an empty socket  .
He also asked about a D-style amp...
The reason behind the conversion is that he can't stand this amp anymore. It stops and comes into the shop, leaves perfectly, then shows up 3 months after with different complaints....
Ideas are very appreciated!! He is a professional musician and gigs 4 to 5 times weekly and is after a clean sound with personality. BTW 2203 was his idea... since he mentioned clean sounds I would be more tempted to do the D-style preamp into a quad of 6550, since P.T. has enough power to run 4xEL34's and 6550 and El34 have the same heater current demand.
What you guys think  about Laney O.T.'s?? Would we benefit changing it for a huge O.T. since cleans sounds are so important?? His distortion is based on SS stuff...

Thanks in Advance
Best Regards

Rzenc
 

[Tiny_Daddy]

I notice turretboards.com sells a JCM800 turret board. If he wants reliable I would start from there.

[nateflanigan]

what about a hi-watt style amp?  I don't know anything about them from a build perspective but as far as playing, clean with a big personality is how I'd describe them. 

[Rev D]

 A Dumble might be pretty cool, they're sort of known I think for they're pre-amp distortions with a cleaner power section, but have a lot of adjustments in the pre-amp. Its my understanding its basically a Fender with a different pre-amp (early examples at least I know Howard converted many Fender Twins and Bassman's). Might be a pretty good go. I know for example his Steel String Singer like SRV used was a 150 watt tube amp that was basically like a bass amp from what I understand. Being as many of these were based on Fenders, I don't think anyone does Clean much better (Well maybe Hi-Watt but they're layout is much different not that I think it would matter circuit wise). My 100 watt marshall was very clean up to a point, then it got that typical british midrange they're known for. Lots of options with that big power supply for sure.

Regards,

Rev. D.

[darkbluemurder]

Hi Folks,
So my friend requested me to convert his Laney GH100L to a JCM 800 2203. ... and is after a clean sound with personality. 

That screams for a JTM-45/100. For more overdrive options you can always add a LarMar PPIMV. 

Cheers Stephan

[rzenc]

I notice turretboards.com sells a JCM800 turret board. If he wants reliable I would start from there.

Yeah! for reliabilty I trust turret boards And Mr. Hoffman's approach to board building makes it easy to work on it when it's necessary. I have built JCM800 and Plexi boards following his guide lines and layout and got very nice results.

what about a hi-watt style amp?  I don't know anything about them from a build perspective but as far as playing, clean with a big personality is how I'd describe them. 

Hiwatt is new ground to me, never heard one in front of me, never had the opportunity to open one up. I'm aware of Mr. Huss's work but not sure if I can handle this. Specially since there seems to be so much hype over hiwatt layout and how it contributes to it's sound...I don't think it could be possible to reproduce that inside a tight laney chassis.

A Dumble might be pretty cool, they're sort of known I think for they're pre-amp distortions with a cleaner power section, but have a lot of adjustments in the pre-amp. Its my understanding its basically a Fender with a different pre-amp (early examples at least I know Howard converted many Fender Twins and Bassman's). Might be a pretty good go. I know for example his Steel String Singer like SRV used was a 150 watt tube amp that was basically like a bass amp from what I understand. Being as many of these were based on Fenders, I don't think anyone does Clean much better (Well maybe Hi-Watt but they're layout is much different not that I think it would matter circuit wise). My 100 watt marshall was very clean up to a point, then it got that typical british midrange they're known for. Lots of options with that big power supply for sure.

I have a D syle, I will let him play and let's see what he thinks. Actually it features a jamestonestack instead of FMV type. 6550 outs. this thing screams.

That screams for a JTM-45/100. For more overdrive options you can always add a LarMar PPIMV. 

Cheers Stephan

I innitialy thought about a 1959 or a 5F8A with ss rectos... but them he  mentioned JCM800.. I will talk to him this weekend and hope he agrees.

I 'll keep you posted.

Thanks in Advance

Best Regards

Rzenc

[Tone Junkie]

Rzenc look up on this forum for the ultimate marshall one of the fine forum members put up a layout (done very well mind you) of a marshall that was half 2203 and all 1959 combining the best of both worlds the laney has 3 preamp tube plus the PI. which is exactly what this one calls for the versatility of that layout would be the best comprimise for your friend. It has everything, With proper lead dress and a good grounding schem and it would be quite as a church mouse at least as quite a as a high gain amp can be . Bill 
my hats off to the fine gentlman that put it together.

[rzenc]

Rzenc look up on this forum for the ultimate marshall one of the fine forum members put up a layout (done very well mind you) of a marshall that was half 2203 and all 1959 combining the best of both worlds the laney has 3 preamp tube plus the PI. which is exactly what this one calls for the versatility of that layout would be the best comprimise for your friend. It has everything, With proper lead dress and a good grounding schem and it would be quite as a church mouse at least as quite a as a high gain amp can be . Bill 
my hats off to the fine gentlman that put it together.

Yeah  I have been following this topic with great interest. Both designs sounds very nice, but I did not talk to my friend yet - lack of time - 
I thought about a 100W one of a kind 1959 P.I. and power amp + 5F6-A preamp and maybe a footswitchable Mr. Hoffman's hot-switch instead of having bass and treble channels. He needs FX loop and last time we talked he mentioned the possible addition of some rack gear and we may install a balanced loop.
The idea is to use the existing chassis and head cabinet and maybe iron. I'm not sure if tube rectos would be a benefit in his specific case. of course we want a toneful amp, but one of his requests was to get ample clean volume for stage playing and i think tube recto would introduce sag when cranked, I mean, more sag than necessary, but you guys are free to shoot if you disagree

Thanks for the reply!
Suggestions are welcome!!!

Best regards

With respect
Rzenc

[rzenc]

So, my friend took an amp that I had laying around and came back asking me if it was possible to build that circuit inside his Laney carcass... well, I felt honored with his kind comments since it was something that I put together and fooled around quite a lot...but instead of a pair of 6550 it will be using a quad of 6L6GC... I still need to plan the O.D. relay switch power supply... but would like to hear from you what you guys think... Please, if you see any error, let me know... I draw it and would be glad if someone else eyes could check it...

Many thanks in Advance
Best Regards

Rzenc

[rzenc]

Hi folks

I was talking to my friend and he said he would like the resonance to be 'on' all the time, but would like to be able to dial it in... I remember seeing a schem on the Library that had a "meat" control that works to add bottom end to the P.I.??? I said I would try to discover if this was the idea behind it and report back... We don't have enough room for another pot on the from panel and we will have an unused spst switch... So my second question is: If we use the switch to turn feedback off how would meat control work?? And how about the presence pot? would they become ineffectively??

Thanks in Advance

Best Regards
Rzenc

 

[sluckey]

If we use the switch to turn feedback off how would meat control work?? And how about the presence pot? would they become ineffectively??

Since both of those controls act upon the feedback signal, I would expect both to have no effect if you remove the feedback.

[rzenc]

Thanks!!!

So I thought about DPDT relay switch to engage the resonance on/off. Does the relay switch Hoffman sells would stand the voltage?

Thanx in advance

Rzenc

[sluckey]

yes

[rzenc]

Thanks sluckey!!!!!!!!!!!

So, I came up with this schem for the mentioned switching resonance. I will use the relay Hoffman sells to build it.  I will be glad if someone points something suspicious about it.
Thanx in Advance

Best Regards

Rzenc

[rzenc]

I will need to power 2 relays and 2 RED LED's. Based on the relay power supply available on the Library to the hot switch mod I draw this one. I have used the Library version with success to power one relay and one LED. What you guys think?

Thanks in advance

Best Regards

Rzenc

[sluckey]

Simplify. You don't need to double up on everything. One power supply can power many small relays. Look at this...

[rzenc]

Thanks Sluckey!!!!!!!
What the change from 4700uF to 100uF means?? Wouldn't it be better to have 'mo' filtering???

R.

[sluckey]

You have 'mo' than enough filtering just with that 4700 and 100. In fact, a couple 470s would be 'mo' than enough for 2 tiny relays and 2 LEDs. Wouldn't you rather have 'mo' room under the hood?

I would also replace those despiking diodes with 1N4148s and save those UF4007s for a high voltage application. But, if I didn't have 1N4148s, I'd use whatever I had handy. I see more 1N4148s across low voltage relay coils than any other diode.

[rzenc]

Yo da man bro! 

I used UF4007 on the drawing because I bought 100's for $2. But will take your advice and use 1N4148. However I would like to understand the difference between them. Why 1N4148 would be better suited for such task instead of UF4007??

Thanks!!

Best Regards

Rzenc

[sluckey]

Fast is a good characteristic for relay despiking diodes. Both diodes are very fast. The 1N4148 is made for small voltage fast switching applications. The UF4007 is a fast diode suited for high voltage/high current applications. At one time the 4148 cost pennies while the UF4007 cost dimes or even dollars. But if you only paid pennies for the UF4007, then cost is no longer a factor.

It's still like using a 50 watt resistor to do the work of a 1/2 watt resistor, although the footprint is basically the same size with the diodes. I would use whichever diode I had on hand, but if I had both types, I'd use the 1N4148 across a mini 5Vdc relay coil (or even a 24vdc coil) and save the UF4007s for high voltage rectifier circuits. Oh, and glass has so much more class than plastic!  

1N4148...     http://www.vishay.com/docs/81857/1n4148.pdf

UF 4007...    http://www.vishay.com/docs/88755/88755.pdf

[rzenc]

Oh, and glass has so much more class than plastic!   

Now I see....

[rzenc]

Preamp board done. waiting ps caps to arrive and chassis is going to sandblast today...

My friend asked about retolexing it - is it  a word?? - with snakeskin tolex - do you guys know a good tutorial about it? I won't be doing this one, but I would like to know how to do it properly.

Thanks in Advance
Best Regards

Rzenc

[rzenc]

Do you think it would be safe to use 1/2W parts on this bias supply?

Thanks in Advance

Best Regards

Rzenc

[rzenc]

I checked the board to see what size of resistors they used and it seems to be 1/4W or even 1/8W these things are sooooo small that may become out of spec if you look too much at them
Also, on the bias schem posted, there are no notes saying it should use higher wattage resistors....and the reason I suspect they are 1/4W - 1/8W is because Laney specifies where 1/2W should be used... So I will go ahead and pop 1/2W parts in there...