Tube rolling and SAC Glowmaster KT88?

First of all, congrats on discovering this amp. There's not to many owmers of this one out there as far as I can tell. Out of interest, what led you to your choice?

I've had a Glowmaster KT88 for a while and have tried using 'winged C' Svetlana KT88's from St Petersburg in place of the SED Svetlana's; to say there was an improvement would be somewhat of an understatement. More depth, clarity, realism and tangible presence. A cracking amp as it is, but changing the output tubes to the winged C's IMHO is a cost effective and dramatic upgrade.

I looked at changing the 6N1p driver tubes, but upon researching this it looks as though whichever manufacturers label is on these, new one's all come from the same factory in Russia. Although there's the option of looking for NOS 6N1p's which seem to come in different flavours as in how closely they were factory matched, differentiated by two letters after the 6N1p i.e. 'EV' or 'IV'.

Thanks for taking the time Hiker to post your thoughts. I was really led to the Glowmaster by a desire to try valves after 10 years or so of solid state. I picked up an Art Audio Concerto power amp earlier in the year to experiment and whilst it was good it didn't quite have the grunt to drive my speakers like my Gamut D200. I emailed George at NorthCreek and he recommended a well designed tube amp of around 70 watts should be ideal. So I poked around a few forums and came across someone who had replaced a D200 with the SAC KT88 and was delighted with it. I checked out the Hifi World review, which seems to be about the only one out there and then bought it without first hearing it...and don't regret it for a second.
I was considering the Winged C myself and I have also heard good things about the Electro Harmonix KT88 generally but your positive experience has probably just tipped the balance in favour of the Svetlanas.
I also did some research into swapping out the 6N1P tubes but like you I found that all new production units are identical. Out of interest have you tried rolling in some NOS 6N1P valves?

Hiker363, I'm confused by your comments regarding the Svetlana tubes.

SED KT88's with a Winged C logo are made in St Petersburg, and Svetlana KT88's with an S logo which were made in St Petersburg preceeded them and are the same tube. The latter haven't been made for many years.

The current Svetlana KT88 is not made in St Petersburg but is often confused by the unwary with the original "Svetlana KT88". It is not marketed as a SED tube.

As I read your comments I suspect you may have been comparing the current SED KT88 (identical to the original Svetlana) with current production Svetlanas, not made in St Petersburg, and which sound (IMHO) very different and justify your observations about the differences.

Well Hiker, I have taken the plunge and ordered a matched quad of winged Cs so thanks for the benefit of your experience. I'll report back in due course and let you know how they behaved in my particular set up. If anyone else has contributions to make to this thread then please don't consider it closed. This Glowmaster amp is a 'keeper' so I'll be interested in any tweaks, which you feel wring the most out of your unit. I have replaced the stock power cable with a Zu Bok which made a significant improvement and I have ordered some LSU No Spikes (I believe they are called "Spike Sound Will" on the other side of the pond) to evaluate for isolation purposes as the amp is too heavy for both my SAP Relaxa and Seismic Sink.
Of course, any alternative tube combinations i'd be fascinated to hear about...

Hi Mghf, just my thoughts but I hope you'll be as happy as I am after substituting the stock tubes with the Winged C's. To my ears, they're in a different league. Mine sounded better than the original tubes from the off, but really started to come alive and 'sing' after about 40 to 50 hours use, so give them a little time to settle in. Like you, I'd been down the solid state route for many years, and discovered incredible detail but never that elusive something. Then along came valves, and 'another convert is made'.

Interestingly, my first experience with valves was listening to an Art Audio Concerto at Definitive Audio in the UK. My speakers are a little on the hungry side regarding current draw, hence researching and eventually setting on the SAC. Like you, I'd come across the chap who'd had a D200 and his comments also swung it for me.

I've toyed with the idea of NOS 6N1p's but been so happy with the sound of late, didn't really get round to it. If you're interested, have a look on Jacmusic.com - they do some pretty inexpensive NOS 6N1p's.

Newbee, As I'm sure you're aware, there's much politics surrounding the Svetlana brand name. As of present there's...

S Logo (on account of the large 'S' printed on the tube); manufactured at the Refelktor factory, marketed by New Sensor; 'officially' no longer sold in Europe.

Winged C Logo; manufatured at St Petersburg, Russia (These are the real McCoy imho); 'officialy' no longer sold in the US

For what it's worth, the Electro Harmonix KT88 seems to me, on close inspection of the build, exactly the same as the S logo Svets. No surprise really, also being marketed by New Sensor, and made at Reflektor. I could be wrong, but they look carbon copies of one another, just with different print on their sides.

I received my Winged Cs yesterday and plugged them in only to find that despite ordering a matched quad, one was severely off and I was unable to bias it whilst another was just alarmingly off, two were spot on. I suppose I would never have known if the Glowmaster didn't have the LCD display!
Consequently they all went back and I probably won't be able to play until next week now when the replacements arrive (fingers are crossed for a Saturday delivery but that really would be the triumph of hope over experience!).
Thanks for the tip about Jacmusic.com Hiker, I'll check out what they're offering whilst I'm in tube limbo.

I have put a few hours on the "C"s now and I'd have to agree with you Hiker, they have made a great amp even better. Better right across the frequency range and a soundstage you could almost step into. Thanks for your advice, it was much appreciated.

That's fine. Glad you liked them. If you've only had several hours on them, bear in mind that after a good 50 hours bedding in time(in my experience) they will sound far better.

Did you persue the NOS 6N1p's?

Hello,
It's been a few years,  what are your impressions of the Glowmaster KT-88 now?  Reliable?  I'm considering it for my system.  Any comments would be appreciated

I just  received the new version of the Glowmaster with a pcb and auto bias circuit.  I must say it is a glorious sounding amp.  It pulls you into the music, revealing and alive.  Likely the best amp I have owned.  I will comment that it has a high noise floor, there is a hum coming from the amp, tolerable yes, but it is there and noticable. 
Has anyone else experienced this?  Solutions?  Different tubes?

I'm looking at this company's GM70 PSET amp. The price is right but I would have a huge problem laying out that amount of money and having any noise,[hum] as part of the deal. 
The PSETs are mono blocks and along with the purchase I may go for their balanced transformers. I think this might reduce any tendency for hum. IDK

Glowmaster = great sound, but reliability could be better

I have been seriously looking at SAC, so this is disconcerting. Kittipol seems straight up and the balanced Glowmaster fits right in with my system. When you say great sound, what are it's strengths?