8600 is a 300B SET after all, although I find it to have better detail and extension compared to the average 300B SET amps.
Before drawing conclusions re 8600 being soft, I can suggest you try the 1960's RCA 6211 tubes in 8600's 12AU7 spots. These 1960's tubes are quite cheap on the Bay and synergizes with 8600 to bring out the top end into balance with the 300B.
RCA6211 by drjlo2, on Flickr
Last edited:
It is all very subjective. I did say "a bit soft" This was not a complaint or a declaration of something wrong. The TU-8600 is a very good amp, but I have heard 300b amps sound far more open and detailed. The TU-8800 is not perfect either but more perfect for me in my system in my room than the TU-8600. I am a realist and just because I own a piece of kit my lack of ego allows me to evaluate honestly.
I modded my TU-8800! I've done the resistor, cap, pot, and transformer upgrades and really enjoyed the amp. Yet one thing that bothered me was the stupid placement of the Z-out jumpers. To adjust the headphone output impedance, you have to remove the face plate and top of the case (which requires removing the big tubes). Super annoying, so I cut a hole in the case and bought jumpers with extended handles on them. Works great, and you can barely even see the cutout with the cover on.
Last edited:
Update:
I have a TU-8800 with all of the recommended upgrades (Lundahl, Takman resistors, Mundorf caps, TKD pot). I started with Brimar 6060 (CV4024) Yellow-T and Gold Lion KT77, and I really enjoyed the amp on a variety of headphones. I measured the output impedance on the lowest Z to be 3.38 ohms, which is very good and allowed me to use low impedance stuff, like Diana Phi, HEDDphone, and Borealis.
Recently, I decided to tube roll a bit. Tung-Sol EL34b are pretty nice, they have a lush midrange and more "tube" sound. My favorite tubes have been the Tung-Sol 7581a. So clean, more punch in the low end, and better imaging. Plus they glow blue which is kinda neat.
I have a TU-8800 with all of the recommended upgrades (Lundahl, Takman resistors, Mundorf caps, TKD pot). I started with Brimar 6060 (CV4024) Yellow-T and Gold Lion KT77, and I really enjoyed the amp on a variety of headphones. I measured the output impedance on the lowest Z to be 3.38 ohms, which is very good and allowed me to use low impedance stuff, like Diana Phi, HEDDphone, and Borealis.
Recently, I decided to tube roll a bit. Tung-Sol EL34b are pretty nice, they have a lush midrange and more "tube" sound. My favorite tubes have been the Tung-Sol 7581a. So clean, more punch in the low end, and better imaging. Plus they glow blue which is kinda neat.
If I may recommend some tubes for the TU-8800. I've tried the Tung Sol 6550 black plates. I'd say it's much warmer and sounds more natural than the KT88 Golden Lion (New Version). I also like the Valvo 12AT7's (BWB version). If you can get your hands on a Valvo 12AT7 I would highly recommend it. Super transparent, natural, and simply amazing.
Don't miss these inexpensive NOS 6F6
Inexpensive TUBE set for TU-8800
I have a lot of Volvo, Telefunken, Mulard, Siemens 12AT7 / ECC81 in stock..
if you are interested,please let me know
Inexpensive TUBE set for TU-8800
I have a lot of Volvo, Telefunken, Mulard, Siemens 12AT7 / ECC81 in stock..
if you are interested,please let me know
I cleaned up a mod I had talked about earlier in this thread. I use the TU-8800 as a headphone amp, so the fact that the Zout adjustment is inside the case really bothered me. Before, I had cut a hole in the case and used extended jumpers. This solution was fine, but I would occasionally drop the jumper into the case and have to go on a fishing expedition.
To clean up the mod, I made a PCB that uses long pin receptacles and Grayhill dip switches. The module plugs onto the Zout adjustment pins and is just about flush with the case. It totally covers the hole, which is another plus. Only downside is that I had to order five of the PCBs lol.
To clean up the mod, I made a PCB that uses long pin receptacles and Grayhill dip switches. The module plugs onto the Zout adjustment pins and is just about flush with the case. It totally covers the hole, which is another plus. Only downside is that I had to order five of the PCBs lol.
So I'm having a weird issue. I was trying out these Mullard 807s (which sound great btw) using adapters. However, when switching to triode mode, I get this really loud popping sound out of both speakers a few seconds after turning the amp on.
This didn't happen with the 8200 so I was wondering if anyone else had this issue when using adapters on the 8800.
This didn't happen with the 8200 so I was wondering if anyone else had this issue when using adapters on the 8800.
An externally hosted image should be here but it was not working when we last tested it.
This is the comment from ELEKIT
Thank you for the link about a headphone impedance of TU-8800.
Hmm, though it is nicely done and sure it must be handy,
This is dangerous. We cannot recommend it.
Those jumper setting locations must be the chassis safety purpose.
We need to balance the issue of convenience and safety...
Mr.Fujita says that at least, the setting of "LOW" or "HIGH" should be inside the chassis.
WE do not recommend it
Thank you for the link about a headphone impedance of TU-8800.
Hmm, though it is nicely done and sure it must be handy,
This is dangerous. We cannot recommend it.
Those jumper setting locations must be the chassis safety purpose.
We need to balance the issue of convenience and safety...
Mr.Fujita says that at least, the setting of "LOW" or "HIGH" should be inside the chassis.
WE do not recommend it
Last edited:
Hello,
I recently got a TU-8800 pre-built with the upgraded Lundahl transformers. However, the amp seems to be clipping on the headphone output. I have tried 3 different sets of output tubes (tung-sol 7581a, genelex KT77 and KT88) as well as two sets of 12AT7s (genelex and mullard), but the same behavior is there so I don't think it is a tube issue. I am using a DAC with standard output voltage so it shouldn't be clipping on the input either. The amp sounds fine up until I turn the volume to around 12 oclock to 3 oclock (depending on which tubes i'm using), and then I start hearing the crackling that sounds like clipping.
Does anyone have an idea what could be causing this? I'm not an experienced DIYer so I don't really know how to troubleshoot this myself, but I do have most of the tools that I think would be needed to fix this if I had some help figuring out whats wrong.
I recently got a TU-8800 pre-built with the upgraded Lundahl transformers. However, the amp seems to be clipping on the headphone output. I have tried 3 different sets of output tubes (tung-sol 7581a, genelex KT77 and KT88) as well as two sets of 12AT7s (genelex and mullard), but the same behavior is there so I don't think it is a tube issue. I am using a DAC with standard output voltage so it shouldn't be clipping on the input either. The amp sounds fine up until I turn the volume to around 12 oclock to 3 oclock (depending on which tubes i'm using), and then I start hearing the crackling that sounds like clipping.
Does anyone have an idea what could be causing this? I'm not an experienced DIYer so I don't really know how to troubleshoot this myself, but I do have most of the tools that I think would be needed to fix this if I had some help figuring out whats wrong.