Hello all! after much lurking and learning as much on my own I finally have some questions for you all. I finished soldering my SSE PCB last night (FUN!) and now I am ready to order parts for the rest of the amp.
1.) I plan on using EH KT-88 tubes, any recs for good 12AT7/GZ-34/5AR4 tubes?
2.) I will not be using the SS rectifier and did not order/instal the FREDs do I need to do anything to the empty PCB terminals? Do I need to hook up a SS/Tube rectifier switch?
3.) I think I am set on using the Edcor CXSE25-8-5K as my OPTs. These seem to be the consensus best bang for the buck, correct? (will be driving fairly efficient paradigm monitor 7 SE3 speakers)
4.) Any issues using the Allied 6K7VG power transformer with my above tube/OPT choice? It is about half the price of the similar Edcor transformers.
5.) Choke choice; I would like to be able to hide the choke in the chassis does this leave the triad C-24X as my only option? What am I giving up by not spending the extra $$ for a larger choke to mount on top? Will the sound be improved that greatly by a larger choke?
6.) Below you will find the digikey part numbers for the IEC and switches I will be using... couldn't find much in the way of recs for these parts, I think these are ok.
IEC= Q203-ND
Cathode FB/UL mode switches= EG4751-ND
Power switch= R1966ABLKBLKEFBLU-ND
Thank you all!! Any feedback is greatly appreciated! This is the first time I have attempted a project like this, so I will take all the help I can get!
1.) I plan on using EH KT-88 tubes, any recs for good 12AT7/GZ-34/5AR4 tubes?
2.) I will not be using the SS rectifier and did not order/instal the FREDs do I need to do anything to the empty PCB terminals? Do I need to hook up a SS/Tube rectifier switch?
3.) I think I am set on using the Edcor CXSE25-8-5K as my OPTs. These seem to be the consensus best bang for the buck, correct? (will be driving fairly efficient paradigm monitor 7 SE3 speakers)
4.) Any issues using the Allied 6K7VG power transformer with my above tube/OPT choice? It is about half the price of the similar Edcor transformers.
5.) Choke choice; I would like to be able to hide the choke in the chassis does this leave the triad C-24X as my only option? What am I giving up by not spending the extra $$ for a larger choke to mount on top? Will the sound be improved that greatly by a larger choke?
6.) Below you will find the digikey part numbers for the IEC and switches I will be using... couldn't find much in the way of recs for these parts, I think these are ok.
IEC= Q203-ND
Cathode FB/UL mode switches= EG4751-ND
Power switch= R1966ABLKBLKEFBLU-ND
Thank you all!! Any feedback is greatly appreciated! This is the first time I have attempted a project like this, so I will take all the help I can get!
1.) I have a NOS Jan Philips 12AT7 becuase that's what I've been using in my guitar amps. I'm pretty happy with it, but will swap it eventually because that's what one does with tube amps
My 5AR4 is a Sovtek and it's been solid so far (a few months). Sovtek seems to get the nod for 5AR4's around here.
2.) Nope, you're good to go. I went the same way.
3.) Can't comment on the CXSE's, but the GXSE's I installed due to size restrictions have been great. I'm not left wanting for any bass, which is what I understand is the biggest hypothetical advantage with the CXSE's. If I would have had the space, I would have bought CXSE's.
4.) You may be under-specc'd on the HT amp rating. George calls for at least 175mA. If you're going to wait on Edcor OPTs anyways, why not grab your PT from them? I used a XPWR155 and get enough juice on the B+ with a 5AR4 (just a few bucks more than the Allied).
5.) Also from Edcor: EDCOR - XC75-2H-200mA. The choke is there primarily to smooth out the DC and reduce hum. At this, any choke is going to be an improvement over the resistor that would otherwise take its place. I used the above and have no hum that I can detect on my 95+ db speakers.
6.) These will work, but you may find it easier to work with switches that mount in a circular hole. You may not have the luxury with the IEC, but you'll wish you did if this is your first time building something like this.
Be sure to post pics of your build!
My 5AR4 is a Sovtek and it's been solid so far (a few months). Sovtek seems to get the nod for 5AR4's around here.2.) Nope, you're good to go. I went the same way.
3.) Can't comment on the CXSE's, but the GXSE's I installed due to size restrictions have been great. I'm not left wanting for any bass, which is what I understand is the biggest hypothetical advantage with the CXSE's. If I would have had the space, I would have bought CXSE's.
4.) You may be under-specc'd on the HT amp rating. George calls for at least 175mA. If you're going to wait on Edcor OPTs anyways, why not grab your PT from them? I used a XPWR155 and get enough juice on the B+ with a 5AR4 (just a few bucks more than the Allied).
5.) Also from Edcor: EDCOR - XC75-2H-200mA. The choke is there primarily to smooth out the DC and reduce hum. At this, any choke is going to be an improvement over the resistor that would otherwise take its place. I used the above and have no hum that I can detect on my 95+ db speakers.
6.) These will work, but you may find it easier to work with switches that mount in a circular hole. You may not have the luxury with the IEC, but you'll wish you did if this is your first time building something like this.
Be sure to post pics of your build!
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I built mine with the Allied 6K7VG, 150mA Power Transformer and the amp works brilliantly. Back 3 or 4 years ago it was a recommendation. Perhaps the spec has been subject to 'ampere creep"?
Mine is in almost daily use since I put in the Gold Lion KT-88s. I'm finally wiring the KT-88 mono blocks I bought the GLs for, 2 years ago, and it looks like I'll have to spring for another pair!
Mine is in almost daily use since I put in the Gold Lion KT-88s. I'm finally wiring the KT-88 mono blocks I bought the GLs for, 2 years ago, and it looks like I'll have to spring for another pair!
This is a good sounding amp with EH 6CA7s, or Shuguang EL-34s or EH-6550s...it's a very good sounding amp with older Svetlana 6550s...
...with the Gold Lion KT-88s I listen to it more than I do my Magnequest powered 45 amp and that's saying a lot!
The GLs do everything better and the illusion of music is more real.
...with the Gold Lion KT-88s I listen to it more than I do my Magnequest powered 45 amp and that's saying a lot!
The GLs do everything better and the illusion of music is more real.
Thank you all for the quick reply! I send edcor an email today asking for some quotes. Would be interested to hear what other peoples experiences have been.
To be honest with the seemingly limitless number of options for the 12AT7 and 5AR4 tubes coupled with the even more limitless options on which is the best I have been unable to make a decision!
Does anybody have any experience with either of these tubes? Does the 12AT7 even have that great of an impact on sound quality or is the 5AR4 rectifier tube play a greater role?
New Fixed Price Tung Sol 12AT7 12AT7A ECC81 Tungsol Pre Amp Tube $11 75 Each | eBay
Electro Harmonix 12AT7 Balanced ECC81 | eBay
To be honest with the seemingly limitless number of options for the 12AT7 and 5AR4 tubes coupled with the even more limitless options on which is the best I have been unable to make a decision!
Does anybody have any experience with either of these tubes? Does the 12AT7 even have that great of an impact on sound quality or is the 5AR4 rectifier tube play a greater role?
New Fixed Price Tung Sol 12AT7 12AT7A ECC81 Tungsol Pre Amp Tube $11 75 Each | eBay
Electro Harmonix 12AT7 Balanced ECC81 | eBay
Actually missed that, didn't realize the switch had an LED. The LED is not really important to me will probably switch that part out.
I had a good experience with Edcor and their transformers seem to have excellent fit and finish. I believe they quoted 5 weeks turnaround on my order, but I had it in 3 weeks.
Don't fret about the choice of tubes too much. Part of owning a tube amp is trying different tubes to tune your sound to your liking. I'd be more inclined to spend extra on the rectifier than the 12at7 because this design (if using the recommended caps in the PS) runs that harder. A low quality rectifier might give up the ghost; a low quality preamp tube would probably just not sound as good as it otherwise might.
If I were going to replace all my tubes today, I'd try out a different 12at7 and KT88s/EL34s, but stick with a Sovtek 5ar4. YMMV!
Don't fret about the choice of tubes too much. Part of owning a tube amp is trying different tubes to tune your sound to your liking. I'd be more inclined to spend extra on the rectifier than the 12at7 because this design (if using the recommended caps in the PS) runs that harder. A low quality rectifier might give up the ghost; a low quality preamp tube would probably just not sound as good as it otherwise might.
If I were going to replace all my tubes today, I'd try out a different 12at7 and KT88s/EL34s, but stick with a Sovtek 5ar4. YMMV!
I can't believe anyone uses rectifier tubes anymore... The heat contribution causes other tubes to age faster, they throw away roughly 40volts of B+, which is a squared term in the power out formula, they cause the power tranny to heat up more, and in many cases where chokes and whimpy filter caps are used the source impedance of the power supply will get high at low frequencies making the bass sound flappy... Solid state diode noise is easily dealt with, and has never been a problem for me. Same thing with Rf AC line noise (if you do your grounding properly). Having said all that, some of those voltage regulator tubes that are technically meager, glow purple, which can add to the art object value of a tube amp.
Bob, I don't think a suitable solid state option has been thoroughly explored for this design as the originally spec'd part has had a bad track record. George hasn't officially published a replacement. Not to say that there aren't options out there, but keeping to the tried and true valve recommendations is a bit easier for beginners.
I wouldn't turn down a little extra b+ though if you have ideas
I wouldn't turn down a little extra b+ though if you have ideas
I have both solid state and tube rectification in my SSE. I prefer using the
5AR4 rectifier that I have in there primarily because of its slow warm up
which results in less stress on the power tubes when the amp is turned on.
I measured B+ at turn on for both tube and solid state rectifiers. With my
power transformer, Edcor XPWR035 and Sovtek 5AR4 rectifier, it takes about
20 secs. for B+ to get up to speed then settles at around 460 volts. When I
switch over to solid state rectification B+ immediately shoots up to around
530 volts then gradually settles down to around 475 volts. I believe this
sudden surge of B+ will be much more detrimental to the other tubes than
any additional heat from the tube rectifier.
5AR4 rectifier that I have in there primarily because of its slow warm up
which results in less stress on the power tubes when the amp is turned on.
I measured B+ at turn on for both tube and solid state rectifiers. With my
power transformer, Edcor XPWR035 and Sovtek 5AR4 rectifier, it takes about
20 secs. for B+ to get up to speed then settles at around 460 volts. When I
switch over to solid state rectification B+ immediately shoots up to around
530 volts then gradually settles down to around 475 volts. I believe this
sudden surge of B+ will be much more detrimental to the other tubes than
any additional heat from the tube rectifier.
After wearing out the JJ 12at7, I picked up a few NOS RCA 6201. the 6201 is a military grade 12at7 and I don't think I paid more per tube and it sounds better and last longer. But you may have to watch ebay a bit to get a deal. I've rolled through a few output tubes (6550, 6l6GC, 350b, el34) and the Tung Sol reissue 6550 is my go to tube. I have not tried any kt88s. I have some Valve Art 350b they are probably my second choice. But if I could only have one type of tube it'd be the 6550.
I use EH Kt88's and a Telefunken 12at7. This combination has given me the most prcise detail accross all frequencies, best power and superb bass. This is running the standard 560ohm resistors, I've yet to change to a resistance more befitting the KT88's.
I also run the CXSE opt's along with a matching Edcor power transformer and choke. Overall, a superb sounding amplifier and its remained in the above guise for some time.
I've tried various tubes in it and none give the results the current setup do which surpass all others in all areas.
I also run the CXSE opt's along with a matching Edcor power transformer and choke. Overall, a superb sounding amplifier and its remained in the above guise for some time.
I've tried various tubes in it and none give the results the current setup do which surpass all others in all areas.
After some additional research I found a thread from 2010
http://www.diyaudio.com/forums/tubelab/174765-simple-se-tubelab-com-2.html
Where a member (nightanole) states that for the SSE amp the GX series OPT are actually better in this amp running KT-88s then the CX series. I placed the quote below... Does anyone have an opinion on this?
"Bigger is better doesnt work as well with output transformers. The gx are only rated to 40hz at full power, but will go lower then 20hz with less power. Upping to the cxes means they want 25 watts, which is a bad match for the amp unless it can provide at least half that. If your running the kt88 (HUGE) in triode mode your only putting out like 7 watts. So ya the smaller guys would sound better."
http://www.diyaudio.com/forums/tubelab/174765-simple-se-tubelab-com-2.html
Where a member (nightanole) states that for the SSE amp the GX series OPT are actually better in this amp running KT-88s then the CX series. I placed the quote below... Does anyone have an opinion on this?
"Bigger is better doesnt work as well with output transformers. The gx are only rated to 40hz at full power, but will go lower then 20hz with less power. Upping to the cxes means they want 25 watts, which is a bad match for the amp unless it can provide at least half that. If your running the kt88 (HUGE) in triode mode your only putting out like 7 watts. So ya the smaller guys would sound better."
I think the 25 watts refers to the maximum power output these OPTs are rated for. That is, they can be used for any SE amplifier up to a maximum power output of 25 watts.
I have the big Edcors in my SSE and I'm very pleased with the performance and do not regret getting them.
Having said that, and from what others have posted, I believe the GXE series of OPTs would also be a good choice for the SSE.
+1 on the sovtek rectifier, I went through a couple other brands until this current sovtek which seems bullet proof. There's also a mod, you can use two uf4007 diodes between the power trafo & the board which seems to help the rectifier survive. On the 12at7 question I finally settled for a 1962 Amperex 6201. Didn't like any of the newer production tubes (only tried JJ, EH & Philips ECG) Best of luck and enjoy your build! Regards, Peter.
The thought behind avoiding a larger-than-necessary OPT (besides cost and bulk) is that the rather large core may introduce it's own distortion and reduce some of the amp's nuance. If you are definitely sticking with triode-strapped KT88s, then you might consider the smaller OPTs. However, if you are going to run UL or pentode and want the amp to really rock, stick with the CXE's. That is what I used on mine and they are great.
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