VTV Push-Pull 6SN7/KT88 Amp: DIY or China?

[88man]

Among my other projects, I am looking for a 50W+ PP 6SN7/KT88 design. This modified Williamson design looks very appealing, however I can't find Plitron 4142 OPT, let alone an Acrosound a To-330 OPT.

1. How will these OPT substitutes sound?...
Edcor: EDCOR - CXPP60-MS-4.2K
BEZ (Chinese): BEZ Push Pull Transformer 80W 4k:4-8ohm 2PCS_PP Transformer_Transformer_Analog Metric DIY Audio Kit Online Store
Schematic: VTVKT88

I would use Sylvania 6SN7GTB and Genalex Gold Lion KT88 tubes, Auricap coupling caps, Hammond power transformer and chokes, and ASC motor run caps in the PSU.


2. Would it be easier to troubleshoot a DIY project OR modify a Chinese amp with upgrade components - a dilemma! The quality seems to be getting more competitive among Chinese offerings. How do the integrated amps compare among: Ming -Da MC-368-B90 vs Cayin A88T vs Doge 6130R vs Yaqin MC-100B?...

Thanks

 

[dowdylama]

You can find the Plitron 4142 by scrolling down this page:
http://www.plitron.com/audio_sd.asp

 

[Eli Duttman]

Only absolutely top notch O/P "iron" should be used in Williamson style circuits. "Budget" trafos simply are not good enough in the phase shift dept. Williamson circuits made with "ordinary" O/P trafos become phase shift oscillators.

JMO, build a Mullard style circuit with 6SN7s in the LTP positions and 12AT7 sections in the voltage gain positions. Mullard style circuity is MUCH less prone to instability than Williamson style is.

 

[88man]

Thanks dowdylama and Eli! It seems the Plitron transformers are spec'd better than Hammonds or Edcors. The cost for a dual mono design with only a single power transformer and two rectifiers PSUs would be around $800 just for the trafos if I went with Plitron. I am sure Lundahl and SAC will be up there too. This is a bit risky, but I'd be curious if others have built this schematic? VTVKT88

 

[bigjppop]

2. Would it be easier to troubleshoot a DIY project OR modify a Chinese amp with upgrade components - a dilemma! The quality seems to be getting more competitive among Chinese offerings. How do the integrated amps compare among: Ming -Da MC-368-B90 vs Cayin A88T vs Doge 6130R vs Yaqin MC-100B?...

Thanks

Thats the question I'm having... The Chinese stuff does seem to be getting really good and its no question it is awesome bang for the buck! I really don't want to be one of those guys that just throws in expensive parts and hopes for the best. I'm interested in seeing the comments your thread generates.

 

[Eli Duttman]

Thanks dowdylama and Eli! It seems the Plitron transformers are spec'd better than Hammonds or Edcors. The cost for a dual mono design with only a single power transformer and two rectifiers PSUs would be around $800 just for the trafos if I went with Plitron. I am sure Lundahl and SAC will be up there too. This is a bit risky, but I'd be curious if others have built this schematic? VTVKT88

Dude,

That's exactly my point. You financially expose yourself substantially, in order to safely employ Williamson topology. Mullard topology is as well proven as Williamson's and it will work just fine with highly affordable Edcor O/P "iron".