View Full Version : 6B4G Monoblocks with Hashimoto Transformers
AD Audio
07-10-2020, 19:03
These amps started in life as some Audio Innovations The First Monos. They were produced by the factory built in AI 800 stereo chassis. Someone got hold of them and added a choke input GZ37 rectified power supply and converted the phase splitter from ECC82 to 5687 operation. The trouble was they got in a frightful pickle in implementing an earth lift system, as well as the heater supply. Worst of all, the chassis was not earthed at all, potentially exposing the user to dangerous voltages. The amp hummed like hell, but did show good promise for sound quality.
The amps have now been totally rebuilt with Hashimoto tranformers and chokes. Heating is all DC regulated. The amps now sound amazing, and run completely silently even on my 96DB speakers. Just as well really as the owner will be using them to drive his £4k headphones!
https://i.imgur.com/BgKp1gN.jpg
https://i.imgur.com/UikROgL.jpg
They also measure incredibly well with those Hashimoto transformers as these photos of 1 and 10khz square waves show
https://i.imgur.com/P6cBrap.jpg
https://i.imgur.com/wN485jx.jpg
Filterlab
09-10-2020, 18:57
Very nice indeed David! They look lovely, I'm sure they sound it too.
Having had no experience with valve amps, what's the reason for having an earth lift system?
Ali Tait
09-10-2020, 19:01
Be these are lovely. Always liked a decent 2a3.
Huh? I thought 6B4G was an octal 6A3.
Ali Tait
09-10-2020, 19:31
Yep. Still the same as a 2a3 though, aside from filament voltage.
WESTLOWER
09-10-2020, 21:35
Great work again David :cool:
Yep. Still the same as a 2a3 though, aside from filament voltage.I ordered a Russian equivalent to 6B4G with an octal to UX4 adapter last week just because they are mega cheap. Will put them in the Lampizator to see what they are like. Not expecting much but you never know.
AD Audio
10-10-2020, 10:31
Very nice indeed David! They look lovely, I'm sure they sound it too.
Having had no experience with valve amps, what's the reason for having an earth lift system?
The earth lift system stops any earth loops happening when you connect ancillary equipment. Works incredibly well and can reduce the noise floor too
AD Audio
10-10-2020, 10:33
I ordered a Russian equivalent to 6B4G with an octal to UX4 adapter last week just because they are mega cheap. Will put them in the Lampizator to see what they are like. Not expecting much but you never know.
Let us know how those valves are. I will be building another pair of these in due course
Ali Tait
10-10-2020, 12:37
I ordered a Russian equivalent to 6B4G with an octal to UX4 adapter last week just because they are mega cheap. Will put them in the Lampizator to see what they are like. Not expecting much but you never know.
Nice, let us know what they are like. 6C4C is it?
Ali Tait
10-10-2020, 12:39
These might be worth a go-
http://www.askjanfirst.de/dindex.htm?/rneu.htm
Nice, let us know what they are like. 6C4C is it?Yup.
I own a lot of triodes and NOS Tung Sol 6A3 is one of my faves. They did 6B4G too. Probably pretty much the same tube.
The Tung Sol 6A3 has a very natural, spacious easy listening nature to it that is really hard not to like. Smooth mid range and treble sounds relaxed where other valves can sound edgy. Big, generous easy going bass, too. Definitely nice.
BTW 6C4C should turn up next week. Less hopeful for the adaptors though as they are coming from HK.
Ali Tait
10-10-2020, 13:14
2a3 and 45 are definitely two of my favourite valves.
My current fave is the Tesla AD1n.
Nice find on the Sylvania - good price.
Filterlab
10-10-2020, 21:14
The earth lift system stops any earth loops happening when you connect ancillary equipment. Works incredibly well and can reduce the noise floor too
Ahh, I see. Thanks.
Ali Tait
11-10-2020, 00:02
My current fave is the Tesla AD1n.
Nice find on the Sylvania - good price.
Yes I thought so.
Nice, let us know what they are like. 6C4C is it?They are excellent so far. I am quite taken back by them TBH.
Just get the most recent ones, not the older ones as I can't vouch for them.
Excellent clarity, linearity, separation, imagery and detail across the frequency range.
Warm? No. Just really clear.
Mine look like this.
https://uploads.tapatalk-cdn.com/20201019/14fafdd60503c68a6a0f26f1e8774765.jpghttps://uploads.tapatalk-cdn.com/20201019/ebc5c8924aef45bebe6c27cf9014dffa.jpg
AD Audio
20-10-2020, 08:52
I found this ad on another well-known Forum relating to the amps:
'Up for sale are “those” 6B4G amps built by Guy Sargent and previously owned by Amdismal amongst others. I have had theses amps now for about 5 years, using successfully with my horns. I am now fully active, and as I don’t have room for 8 channels of tubes, they have been sat gathering dust. So I have decided to allow someone else to enjoy them. As you can see from the picture they aren’t a looker, but the rich midrange will make you forget about it’s looks. The previous owner, Tom, added the cherry wood surrounds to bling them up a bit. The amps will come with a number of spare tubes, currently they are using Russian power tubes, but I have USA ones it came with too. I am going to the Kegworth show, so can bring them there, too fragile to post imho. I am sure I could convince Steve57 to connect them up to his speakers in place of his PX25’s for an audition. They can be auditioned at mine in Nottingham too, (only one channel not full range as I am active). I am selling them for the same price as I bought them.'
I spoke to Guy about the amps and clearly someone got at them after he built them!
walpurgis
20-10-2020, 09:19
2a3 and 45 are definitely two of my favourite valves.
Yes. Not really planning to get back into valves in a big way, but I could be tempted by something 2A3 wise :).
I just got some Amperex 45s that are really the same as Philco 45s. They measure superbly. They sound shit in my DAC.
Shame.
Not all 45s are equal.
BTW the 6C4C sound NOTHING like Tung Sol 6A3.
AD Audio
20-10-2020, 19:15
I just got some Amperex 45s that are really the same as Philco 45s. They measure superbly. They sound shit in my DAC.
Shame.
Not all 45s are equal.
BTW the 6C4C sound NOTHING like Tung Sol 6A3.I've ordered some of the 6C4cs now. Just got to build the next amp [emoji2]
Sent from my ONEPLUS A5000 using Tapatalk
Ali Tait
20-10-2020, 21:17
They are excellent so far. I am quite taken back by them TBH.
Just get the most recent ones, not the older ones as I can't vouch for them.
Excellent clarity, linearity, separation, imagery and detail across the frequency range.
Warm? No. Just really clear.
Mine look like this.
https://uploads.tapatalk-cdn.com/20201019/14fafdd60503c68a6a0f26f1e8774765.jpghttps://uploads.tapatalk-cdn.com/20201019/ebc5c8924aef45bebe6c27cf9014dffa.jpg
Nice looking valves, sound like they hit the spot.
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