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Pilot SA-232...Can it rock?

Hey just checking in here. So the pilots been running very nicely, I’ve had it hooked up for a while now with matched tube amp doctor el84s, tele 12ax7s and an RCA clear top 12au7 phase inverter tube. It’s hooked up to my Mac C29 preamp and Altec boleros 890cs.

the short of it is that this amp can sound pretty special sometimes but often I’ve noticed it’s been fairly fatiguing to listen to for extended periods. Not sure what about the amp, but the rest of my system did not have this sort of shouty aggressive tone to it when I was running my tech’s eico 22 monoblocks (6L6 tubes) for instance (all other components the same as now). I mean it can be like ice pick to the ears level harsh with guitars and rock especially, even at moderately loud volumes. I find myself just wanting to turn my system off more often than not.

Should I try different el84s or a 12au7 phase tube before deciding this isn’t the amp for me? I’ve swapped the tele 12ax7 tubes with a pair of RCAs to no avail. Any thoughts? Thanks. The amp has a recap with orange drop capacitors
 
MadcapLaughs said:
Hey just checking in here. So the pilots been running very nicely, I’ve had it hooked up for a while now with matched tube amp doctor el84s, tele 12ax7s and an RCA clear top 12au7 phase inverter tube. It’s hooked up to my Mac C29 preamp and Altec boleros 890cs.

the short of it is that this amp can sound pretty special sometimes but often I’ve noticed it’s been fairly fatiguing to listen to for extended periods. Not sure what about the amp, but the rest of my system did not have this sort of shouty aggressive tone to it when I was running my tech’s eico 22 monoblocks (6L6 tubes) for instance (all other components the same as now). I mean it can be like ice pick to the ears level harsh with guitars and rock especially, even at moderately loud volumes. I find myself just wanting to turn my system off more often than not.

Should I try different el84s or a 12au7 phase tube before deciding this isn’t the amp for me? I’ve swapped the tele 12ax7 tubes with a pair of RCAs to no avail. Any thoughts? Thanks. The amp has a recap with orange drop capacitors
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Interesting. I’m going to chime in on this as I’ve had a similar experience.

I’m not familiar with your Boleros but looked them up and saw that they have a horn tweeter (mid too?). I had been running Klipsch Heresys and now have Forte III.

My first experience with sharp and painful using a tube amp, as you describe, was with a Fisher 300b EL34. I was in the same boat as you are now, baffled as to why the amp didn’t sound smooth and pleasant to listen to on my setup.

I moved on from that amp and purchased a Fisher 400. WHOLE new sound. Just beautiful and easy to listen to for hours on end. I also have a couple of EL84 amps. For me, it depends on the kind of music I’m listening to. Jazz, I stick with the Fisher 400 with all those trumpets and saxophones.

One thought is your room. Lots of hard surfaces? That can play a huge roll in contributing to harsh sound. Also, my experience is the EL84s are wonderful tubes but a little more on the “precise” end of the tube sound. That’s my opinion, of course.

On my single ended EL84 amp I experienced a bit of what you described using JJ tubes. I purchased a matched pair of 1963 RCA tubes and it was like night and day. Soundstage opened up and the amp became much more pleasant to listen to.

I know that’s not a ton of useful info but I hope what I posted here gives you some clues in finding out where the issue is. I’m sure more experienced folks will chime in.
 
Ya, i honestly don't think there are any issues with my pilot technically, its running perfectly fine, I think its just the nature of the amp to a certain extent. I just ordered a mullard NOS 12au7 to sub in place of the 12au7 RCA clear top tube i have currently, its the only tube i haven't tried subbing in yet.

I did buy these tube amp doctor tubes to replace the original mullard el84s that were on their way out based on the tube tester values. Now i'm tempted to throw them back in as worn out as they are, i just dont want them to fail, they are all bad values lol. Still im hesitant to shell out more money on pricey vintage el84s as im unsure they will resolve the overall unforgiving tone of this pilot. Im really on the fence about just sending this amp packing to the next buyer and using the funds for a smoother tube amp. choices choice.

on an off note, how do you like the controversial phono stage on your fisher?
 
MadcapLaughs said:
on an off note, how do you like the controversial phono stage on your fisher?
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Good question. I wasn’t aware the phono section on the Fisher 400 was controversial but, with that said, I don’t use it (maybe for the reasons it’s controversial?). I run an external tube phono stage into the aux in on all my amps. I’ve been happy with this arrangement as, after a ton of experimentation, I found that the phono give the amps a bit more “punch” while retaining the tube sound and smoothness.

Im set up with rca and speaker switching so I can change amps at will. Currently I have the Fisher 400, a Gillespie Magnavox SE EL84 (which is outstanding), a Pilot 240 and a little Magnavox 196-00 (mostly use it for fun and not “serious” listening. But it’s really a cool little amp).

I’m actually moving on from the 400 (once I have a buyer) and am really interested in the Schiit Aegir with a tube pre or perhaps a McIntosh SS pre. The Schiit got rave reviews as an affordable class A amp (well, mostly class A. Read up on it for details). Reviews have said it can compete with much more expensive amps.

But I digress. I wouldn’t give up on the Pilot just yet. But I will say a Fisher 400, 500, 800, to me, will instantly cure that harshness problem. Again, my opinion. YMMV.
 
MadcapLaughs said:
Hey just checking in here. So the pilots been running very nicely, I’ve had it hooked up for a while now with matched tube amp doctor el84s, tele 12ax7s and an RCA clear top 12au7 phase inverter tube. It’s hooked up to my Mac C29 preamp and Altec boleros 890cs.

the short of it is that this amp can sound pretty special sometimes but often I’ve noticed it’s been fairly fatiguing to listen to for extended periods. Not sure what about the amp, but the rest of my system did not have this sort of shouty aggressive tone to it when I was running my tech’s eico 22 monoblocks (6L6 tubes) for instance (all other components the same as now). I mean it can be like ice pick to the ears level harsh with guitars and rock especially, even at moderately loud volumes. I find myself just wanting to turn my system off more often than not.

Should I try different el84s or a 12au7 phase tube before deciding this isn’t the amp for me? I’ve swapped the tele 12ax7 tubes with a pair of RCAs to no avail. Any thoughts? Thanks. The amp has a recap with orange drop capacitors
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That's a bit surprising, I've never found my 232 to be harsh at all, but then I don't have horn type speakers.

The most obvious thing . . . I assume your Mac preamp has tone controls. Try adjusting the treble down a notch or two. Actually I'd turn it all the way down and then adjust it upwards until you find whatever setting that sounds best.

To smooth the amp out a bit I'll offer two suggestions.

Try some PIO coupling caps, either vintage Vitamin Q's or get some Russian K40Y-9s, which will likely be easier to find and cheaper. Use the same value as stock.

Also, use 5751s in place of the 12AX7s. That will make more of a difference than using a different tube for the phase inverter.
 
Never heard the term "shouty" in reference to amplifiers—horn speakers, yes, but not amps. I restored my SA-232 using Russian PIO caps and have listened to it paired with a Dynaco PAS 3X preamp and driving my Valencias. Sounds amazing...

Sometimes the synergy between components just isn't right—you might want to look into a tube preamp stage to run with the Pilot, or move up to a higher sensitivity horn speaker (or move to a non-horn speaker...) I had a McIntosh SS preamp stage with a McIntosh tube power amp at one point, and it just seemed anemic but also brittle, compared to the tube preamp stages I'd been using, but YMMV...

A few shots of my SA-232....


index-1.jpg

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I was wondering if you needed to make any adjustments to be able to use the 5751 tube in the pilot amp? If you think that’s a way to make a noticeable difference in the tonal quality amp I may try that out. Also I have a Mullard nos 12au7 on the way right now so I’ll see if that makes any difference. thanks for the suggestion on the PIO Russian capacitors, i May replace the orange drops with those as well. Is it just the main coupling caps that you would say make a big difference? I’m curious on making some mods to this amp and giving it another shot. I’m also using those tube amp doctor el84s right now but I want to grab a back up pair to try and change the sound characteristics for the better. Any ideas on those? Too bad my quad of Mullards it originally came with have all but crapped out.
 
MadcapLaughs said:
I was wondering if you needed to make any adjustments to be able to use the 5751 tube in the pilot amp? If you think that’s a way to make a noticeable difference in the tonal quality amp I may try that out. Also I have a Mullard nos 12au7 on the way right now so I’ll see if that makes any difference. thanks for the suggestion on the PIO Russian capacitors, i May replace the orange drops with those as well. Is it just the main coupling caps that you would say make a big difference? I’m curious on making some mods to this amp and giving it another shot. I’m also using those tube amp doctor el84s right now but I want to grab a back up pair to try and change the sound characteristics for the better. Any ideas on those? Too bad my quad of Mullards it originally came with have all but crapped out.
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So did you try adjusting the tone controls on your preamp, as I suggested?

The 5751 will drop right in with no adjustments needed. It has a bit less gain (mu 70 vs 100 for 12AX7) and I've found they usually sound a bit warmer depending on the circuit.

The PIO coupling caps will probably make a bigger difference than the 5751s. And the K40Y-9s are not super expensive. Use the same values as stock.

But first things first - the tone controls are there for a reason. Use them. Although, after reading @BassKulcha 's comments about his SS Mac preamp, I wonder if that might be the problem. If you have another pre, give it a try. Or maybe just eliminate the pre if you have another way to control the volume - either a "passive pre" (aka a volume pot) or maybe your source has a variable output control (computer, phone, etc). You probably don't really need any gain before the amp.
 
I'm sort of curious if a 5751 would upset the phase inverter balance though. These run a paraphase inverter so its all somewhat dependent on the gain of each section to balance it all out properly.

make sure all of the resistors are on value too, if the stuff around the inverter is off, or the resistors around the 12au7 are off it will mess with how it performs and probably not in a positive way. The 12au7 has a 1M feedback resistor around it and if that goes out of spec it can affect the response of that stage.
 
Perhaps it's already been suggested, but you could try a different tap on your transformer without modifying anything and without any risk of accidentally damaging something, and the change in reflected impedance may get your output tubes into their happy place.
(If you're on 8 ohms, try 4, and check phase while you're at it)
Also, old mullards that look like charred black lumps of coal, are usually not even close to worn out. It's well known that they get nasty black streaks inside and it has no negative effect on performance. If those streaks are the reason you pulled em, maybe put em back...
 
No
trainbuftony said:
Perhaps it's already been suggested, but you could try a different tap on your transformer without modifying anything and without any risk of accidentally damaging something, and the change in reflected impedance may get your output tubes into their happy place.
(If you're on 8 ohms, try 4, and check phase while you're at it)
Also, old mullards that look like charred black lumps of coal, are usually not even close to worn out. It's well known that they get nasty black streaks inside and it has no negative effect on performance. If those streaks are the reason you pulled em, maybe put em back...
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No I know for sure the mullards all failed on my techs tube tester, way into the “bad” range, I was having a red plate issue with them when I first bought the amp, so I replaced them, but it was still red-plating. So I found that the issue was really the tube sockets were loose and haven’t had any issues since. But maybe I could throw them back in for the hell of it and see how they do. I will need to really find another quad of rcas or Mullards though if I’m going to go back to vintage tubes.
Also regarding the tone controls on the preamp, I tried that to now avail, it simply had the same hard glare to the sound with less frequency extension. I’m pretty sure I’m going to go the PIO route (hope they don’t leak all over the place). Anyone know the exact coupling cap values on this sa 232? I’m too lazy. I think I’ll take the Russian cap route. And I’m assuming I’ll just need four of the coupling capacitors.
 
MadcapLaughs said:
Also regarding the tone controls on the preamp, I tried that to now avail, it simply had the same hard glare to the sound with less frequency extension.
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Again, try it with either a different preamp or use a source with a variable output and no preamp.

MadcapLaughs said:
I’m pretty sure I’m going to go the PIO route (hope they don’t leak all over the place). Anyone know the exact coupling cap values on this sa 232? I’m too lazy. I think I’ll take the Russian cap route. And I’m assuming I’ll just need four of the coupling capacitors.
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Yes, there are four of them. They are .1uf 400v. Use the K40Y-9 if you can find them. Of course you can go higher in voltage if you can't find any rated at 400v.
 
https://www.ebay.com/itm/NOS-Vintag...396289?hash=item1ca06a2981:g:S30AAOSwbe5adzUP
I didn’t waste any time, just bought 4 of these. They look like the exact caps and values you stated. Looking forward to installing them.
Also I’ll have to try just using my phone into the line in section of the 232 and use my volume control to see what the amp sounds like on its own. I also have a fisher 400c preamp getting fixed up right now that I’ve never heard. I’m hoping that will bring better synergy, but it could take some time before I get it back.

my taps only show 16 and 8. No 4ohm taps. Not sure if switching to the 16 taps for my speaker cables would yield any better sound, maybe it’s worth a try. I’m just running the simple 8ohm load of the altecs.
 
The 8 ohm is likely the best you're going to do.
"For your speaker cables"
What do we need to know about your speaker cables?
For a sanity check wire up your speakers with copper lamp cord. The cheapest you can find.
If theres any sort of "network" in your cables, you want to eliminate that.

You need to find the problem, adding variables only serves to further obscure your results.
Process of elimination works.
Process of band aid addition, usually doesnt.
 
ok reporting back here, i changed a few things up in my system, mainly replacing my Mcintosh C29 preamp with a Fisher 400c tube preamp, man what a night and day difference. It honestly removed all of that glare and fatigue in my system. So glad I decided to keep the pilot 232, it has tremendous synergy with this fisher. I really liked the C29 matched up to pretty much every other amp besides the pilot, must have just been an unhappy marriage. Seriously this is really meshing into one of the best setups ive heard.

I also subbed a mullard 12au7 in place of the rca on the pilot. I cant tell if that made an improvement, but it certainly didnt hurt
 
Can it rock? Absolutely.
Does it rock as hard as other amps? I guess that depends on the rest of the system and listener.

My recently acquired SA-232 sounds very pleasant. It's beautiful at my usual listening levels. My only gripe is that it runs hotter than any amp I've ever touched or measured. It's a time bomb.

How does it sound compared to my Fisher SA100 or Fisher SA300? They're all good, I can't say I've chosen a favorite.
 
MadcapLaughs said:
ok reporting back here, i changed a few things up in my system, mainly replacing my Mcintosh C29 preamp with a Fisher 400c tube preamp, man what a night and day difference. It honestly removed all of that glare and fatigue in my system. So glad I decided to keep the pilot 232, it has tremendous synergy with this fisher. I really liked the C29 matched up to pretty much every other amp besides the pilot, must have just been an unhappy marriage. Seriously this is really meshing into one of the best setups ive heard.

I also subbed a mullard 12au7 in place of the rca on the pilot. I cant tell if that made an improvement, but it certainly didnt hurt
Click to expand...

I am a little late to this but I have noticed that a few of my tube amps really do not like my restored Mac C-26 or my restored C-28. Both pres get along with many of my amps but my Leak stereo 20 and my Dynakit Mark IVs don't seem to like what the Macs put out. Glad you got a combo that worked out. I have a FA-690 Pilot pre-ceiver and a SA-232 that I hope to get up and running this year.
 
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