First amplifier build
Hey everyone, apologies for the length of this post.
I've just got my Simple P-P up and running. I'm 25 and it's the first electronics project I've taken on, besides a few guitar pedals, so I've got quite a few questions I was hoping one of you more experienced builders could help me out with.
I built the amp, wired it all up, tested out all the grounding and continuity and then switched it on in various stages. First full switch on was terrifying but all went OK, in fact there was so little noise I thought the amp hadn't worked at all. In triode mode it's not really powerful enough to get enough volume out of my speakers (celestion ditton 33s) without pushing into distortion, but in ultralinear mode it sounds fantastic! And I haven't even set up negative feedback yet.
I went for a symmetrical layout and took the risk with wires from pcb to valve sockets. I chose a large chassis so I could space things out a bit, and put the inputs on the front side like the great Ongakus (http://www.sibatech.co.jp/kondo/img/Ongaku.jpg), to minimise noise. I also took the power supply off-board so I could position it near the rectifier and power transformer. So far the risk seems to have paid off, this amplifier is totally silent. Except when playing music that is…
Transformers - Hammond 370HX and 1650FA
Choke - Hammond 159S
Valves - JJ GZ34, JJ EEC81s and JJ EL84s
Power switch - DPST rotary on front
100k alps volume pot
3-way input selector switch
all resistors, capacitors and pcb from George at tubelab.com
Transformers, chassis and valves from Philip at bluebellaudio.com (UK based) who has also given me lots of valuable advice.
Questions:
- firstly, do all my voltage readings look correct?
- should all the heaters be reading 6vac or 12vac? or could it be my cheap multimeter?
- is a 3v variation between the different output valves acceptable?
- I don't have the means to test out what value capacitor to use for negative feedback, I have some 470pf silver mica caps, will they do the job?
- I've grounded the PCB to the chassis with a wire to the left negative feedback terminal, is a screw-down terminal safe for this job?
- I cut holes for 4 and 8 ohm speaker posts before I realised I could only hook one up to feedback at a time. So my workaround is a 3 position ON-OFF-ON 250VAC@15A DPDT feedback switch, with the top ON position for 8 ohms and the bottom ON position for 4 ohms. Is this a good idea or is there a better solution? Will I be able to use this switch with the amplifier on?
- I've bought 2 heavy duty 4PDT switches which I plan to make a 3-way triode-UL-pentode switch system for. They claim to tolerate 250VAC@15A and 380VAC@10A. Is that sufficient? Will I be able to use the switches with the amplifier on?
multimeter readings
High tension - 319 volts
Left ECC81/12at7
1- 202v
2- 104.7v
3- 106.6v
4- 2.8vac
5- 2.8vac
6- 104.7v
7- 0v
8- 0.87v
9- 0v
Right ECC81/12at7
1- 193.4v
2- 110.3v
3- 112v
4- 2.8vac
5- 2.8vac
6- 110.4v
7- 0v
8- 0.85v
9- 0v
Left lower EL84
1- 0
2- 0
3- 11v
4- 2.8vac
5- 0
6- 0
7- 317v
8- 0
9- 319v
Left upper EL84
1- 0
2- 0
3- 10.8v
4- 0
5- 2.8vac
6- 0
7- 318v
8- 0
9- 320v
Right lower EL84
1- 0
2- 0
3- 11.4v
4- 2.8vac
5- 0
6- 0
7- 315v
8- 0
9- 317v
Right upper EL84
1- 0
2- 0
3- 11.4v
4- 0
5- 2.8vac
6- 0
7- 315v
8- 0
9- 317v
Photos
Hey everyone, apologies for the length of this post.
I've just got my Simple P-P up and running. I'm 25 and it's the first electronics project I've taken on, besides a few guitar pedals, so I've got quite a few questions I was hoping one of you more experienced builders could help me out with.
I built the amp, wired it all up, tested out all the grounding and continuity and then switched it on in various stages. First full switch on was terrifying but all went OK, in fact there was so little noise I thought the amp hadn't worked at all. In triode mode it's not really powerful enough to get enough volume out of my speakers (celestion ditton 33s) without pushing into distortion, but in ultralinear mode it sounds fantastic! And I haven't even set up negative feedback yet.
I went for a symmetrical layout and took the risk with wires from pcb to valve sockets. I chose a large chassis so I could space things out a bit, and put the inputs on the front side like the great Ongakus (http://www.sibatech.co.jp/kondo/img/Ongaku.jpg), to minimise noise. I also took the power supply off-board so I could position it near the rectifier and power transformer. So far the risk seems to have paid off, this amplifier is totally silent. Except when playing music that is…
Transformers - Hammond 370HX and 1650FA
Choke - Hammond 159S
Valves - JJ GZ34, JJ EEC81s and JJ EL84s
Power switch - DPST rotary on front
100k alps volume pot
3-way input selector switch
all resistors, capacitors and pcb from George at tubelab.com
Transformers, chassis and valves from Philip at bluebellaudio.com (UK based) who has also given me lots of valuable advice.
Questions:
- firstly, do all my voltage readings look correct?
- should all the heaters be reading 6vac or 12vac? or could it be my cheap multimeter?
- is a 3v variation between the different output valves acceptable?
- I don't have the means to test out what value capacitor to use for negative feedback, I have some 470pf silver mica caps, will they do the job?
- I've grounded the PCB to the chassis with a wire to the left negative feedback terminal, is a screw-down terminal safe for this job?
- I cut holes for 4 and 8 ohm speaker posts before I realised I could only hook one up to feedback at a time. So my workaround is a 3 position ON-OFF-ON 250VAC@15A DPDT feedback switch, with the top ON position for 8 ohms and the bottom ON position for 4 ohms. Is this a good idea or is there a better solution? Will I be able to use this switch with the amplifier on?
- I've bought 2 heavy duty 4PDT switches which I plan to make a 3-way triode-UL-pentode switch system for. They claim to tolerate 250VAC@15A and 380VAC@10A. Is that sufficient? Will I be able to use the switches with the amplifier on?
multimeter readings
High tension - 319 volts
Left ECC81/12at7
1- 202v
2- 104.7v
3- 106.6v
4- 2.8vac
5- 2.8vac
6- 104.7v
7- 0v
8- 0.87v
9- 0v
Right ECC81/12at7
1- 193.4v
2- 110.3v
3- 112v
4- 2.8vac
5- 2.8vac
6- 110.4v
7- 0v
8- 0.85v
9- 0v
Left lower EL84
1- 0
2- 0
3- 11v
4- 2.8vac
5- 0
6- 0
7- 317v
8- 0
9- 319v
Left upper EL84
1- 0
2- 0
3- 10.8v
4- 0
5- 2.8vac
6- 0
7- 318v
8- 0
9- 320v
Right lower EL84
1- 0
2- 0
3- 11.4v
4- 2.8vac
5- 0
6- 0
7- 315v
8- 0
9- 317v
Right upper EL84
1- 0
2- 0
3- 11.4v
4- 0
5- 2.8vac
6- 0
7- 315v
8- 0
9- 317v
Photos
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
spp troubleshooting
Hey guys,
The spp was making a scratching noise and only one channel was working. I then switched it off and put it back on and there was no output.
Rewinding a few nights, I was playing it and I forgot it on and went to bed next morning I realised it was on and took it off.
I took it apart and the resistor 110, 210, 114, 214 are open and the couple g caps are gone as well. Any reasons why that might have happened?
I'm using a Hammond 372hx and every thing else is fine.
Hey guys,
The spp was making a scratching noise and only one channel was working. I then switched it off and put it back on and there was no output.
Rewinding a few nights, I was playing it and I forgot it on and went to bed next morning I realised it was on and took it off.
I took it apart and the resistor 110, 210, 114, 214 are open and the couple g caps are gone as well. Any reasons why that might have happened?
I'm using a Hammond 372hx and every thing else is fine.
Found the gremlins
As it turned out the resistor (R1) had drifted away from 150 ohms (wirewound in cement) and resistors 110, 210, 114, and 214 (all Takman metal) were open. I've replaced all resistors with same make replacements.
Mind you I had replaced all tubes suspecting that one was faulty. It turns out none of them were. The JJs' EL-84 have a very nice tone but don't sparkle like the JJ cryo edition. They are well worth the money. Next upgrade will be Psvane all round.
I am looking at the Hammond 159r choke as a replacement for R1 as I've had a few issues with it from day one. The first resistor I had in there burned the board. It was a mils 150ohm 5W and it was small for the rated power but nonetheless it was the correct rating. It didnt last as and smouldered within days. Luckily it didnt do too much damage to the board.
I will get the choke this weekend and report on how it works.
As it turned out the resistor (R1) had drifted away from 150 ohms (wirewound in cement) and resistors 110, 210, 114, and 214 (all Takman metal) were open. I've replaced all resistors with same make replacements.
Mind you I had replaced all tubes suspecting that one was faulty. It turns out none of them were. The JJs' EL-84 have a very nice tone but don't sparkle like the JJ cryo edition. They are well worth the money. Next upgrade will be Psvane all round.
I am looking at the Hammond 159r choke as a replacement for R1 as I've had a few issues with it from day one. The first resistor I had in there burned the board. It was a mils 150ohm 5W and it was small for the rated power but nonetheless it was the correct rating. It didnt last as and smouldered within days. Luckily it didnt do too much damage to the board.
I will get the choke this weekend and report on how it works.
Hey guys,
I've just ordered a SPP board.
I'm looking at the Edcor XPWR066 (Power transformer for a 240V, 50/60Hz. line to 600V (300-0-300) at 200mA center tapped, 6.3V at 4A and 5V at 3A) and Edcor CXPP25-MS-7.6K (25W, push-pull tube output transformer for 7.6K Ohms to 4, 8 and 16 Ohms.) I'll be driving Mission 761 speakers (89db, 8ohm).
I'd be grateful for advice on tube selection. Is there much to choose between the different brands, or should I just go for the JJ 12AT7 and EL84. With the latter, am I better of with a JJ 5AR4 rectifier or a 5U4? I undertsand one drops more voltage that the other, but I'm not sure if that's going to be an issue with the JJ EL84s and the Edcor power tranny.
Cheers,
Jon
I've just ordered a SPP board.
I'm looking at the Edcor XPWR066 (Power transformer for a 240V, 50/60Hz. line to 600V (300-0-300) at 200mA center tapped, 6.3V at 4A and 5V at 3A) and Edcor CXPP25-MS-7.6K (25W, push-pull tube output transformer for 7.6K Ohms to 4, 8 and 16 Ohms.) I'll be driving Mission 761 speakers (89db, 8ohm).
I'd be grateful for advice on tube selection. Is there much to choose between the different brands, or should I just go for the JJ 12AT7 and EL84. With the latter, am I better of with a JJ 5AR4 rectifier or a 5U4? I undertsand one drops more voltage that the other, but I'm not sure if that's going to be an issue with the JJ EL84s and the Edcor power tranny.
Cheers,
Jon
I grabbed a great deal on some Made In Japan EL84's (Matsushita) they sound really nice, especially with their matching 12AT7's.
The JJ's are nice also but I had the fortune to pick up some NOS TungSol 12AZ7's and they sound really nice up front also.
I popped my JJ 5AR4 within 30 minutes of firing it up so I ran to the guitar store and bought a GrooveTube 5U4, it worked well and I took advantage of the extra 30V of drop so I could try my IBM 6414's up front, Again a superb choice the soundstage was huge with these guys.
Now I run my Hitachi 5AR4 seamed top in my Simple P-P with all Japanese tubes and it works just dandy.
Once I can grab a reasonably priced VT-244 rectifier I will try my 6414's again.
I've been wanting to try the Telam or Polam EL84's also.
The JJ's are nice also but I had the fortune to pick up some NOS TungSol 12AZ7's and they sound really nice up front also.
I popped my JJ 5AR4 within 30 minutes of firing it up so I ran to the guitar store and bought a GrooveTube 5U4, it worked well and I took advantage of the extra 30V of drop so I could try my IBM 6414's up front, Again a superb choice the soundstage was huge with these guys.
Now I run my Hitachi 5AR4 seamed top in my Simple P-P with all Japanese tubes and it works just dandy.
Once I can grab a reasonably priced VT-244 rectifier I will try my 6414's again.
I've been wanting to try the Telam or Polam EL84's also.
Last edited:
I didn't remember seeing your email (I would have noticed that name) so I went back and searched all incoming email for the mid November time frame......not there. After some digging, it seems that several legitimate incoming email messages have been sent to my spam box, while considerable spam still finds it's way into my inbox. I will contact my web hosting company tomorrow morning. This has happened before. A couple of years ago their system decided that Paypal was a spammer and all incoming orders went into the bucket!
I do have plenty of all three boards in stock and plan to keep it that way. Old pricing is still good for now, but I will have to raise international shipping next year, I currently lose $10 on each international shipment.
There will be some new boards next year and a complete update of my web site. One new board is already in house but untested, since I currently have no lab. I am currently rebuilding my lab since I have lost my job and moved 1200 miles. Tubelab is starting over in a BIG empty basement.
The vendor screwed up my last board order too......The last batch of SPP's and TSE's came in gold plated, at the solder clad price. They were sent to the wrong (old) address even though the paperwork clearly shows the correct address. Fortunately Fedex left $1800 worth of PC boards on my daughter's front steps since she lives in our old house.......did I call up and complain about the gold?????
Your user and email name would lead me to believe that you are interested in analog synthesizers? I built the PAIA 2700 in the early 70's, and regret selling my white face Odyssey, Little Brother, and pair of original Univox Mini Korg's (all interconnected) in the 80's.....so I have started designing a new analog (1V / OCT) synth from the ground up. The first non tube product from Tubelab???? Too soon to tell.
That is too cool, there's nothing like analog synth. It's actually supposed to be "bertmoog", after a Moog Micromoog we affectionately named Bert. I misspelled it when I first created the diyaudio account.
I'm not trying to tell you how to run your business, but I don't think people would mind paying $10 more per board. I wouldn't mind paying more just for the board, much less shipping. I bought an SSE and have been enjoying it for three years now.
Also, FYI, I just ordered a TSE.
Thanks for all you do.
.
My mistake...it was the SPP and the SSE boards and one of my prototype boards that came in with gold plating.
I'd like to buy some of those boards with gold plating from you at the solder clad pricing!
OK, no problem. They didn't cost me any more, so they are still $35 while I have them. I got quite a few, and sales are way down in general compared to last year, so I should have them for a while.
The next batch probably will be solder clad. I'm guessing that it was because they had a process problem, a machine down or something, since it was everything I ordered in a two week period last October. My last small batch came in solder clad.
I took a picture of some gold boards, but I keep getting "upload failed" errors....I will try to post the picture later.
