- Feb 4, 2019
I will admit, the tall thin caps Bob installed in the power supply were better than the stock ones the Audion tech used to replace them with when he rebuilt the power supply.I'll restate as previously: I bought those amps as the original owner directly from Audion, then in the UK. I made no changes to them myself other than tubes. About four years in, one of the solid state rectifiers blew. I took both amps to Bob Hovland and asked him to replace and upgrade the rectifiers in both amps so they would be the same. I also asked Bob to inspect the amps for any other problems worth correcting and to make suggestions for improvements he thought worthwhile making.
Bob replaced and upgraded the rectifiers in both amps. He suggested recapping the power supply to get faster charge/discharge than the stock caps, which would improve dynamics, definition and bass. I agreed. He also said he could make the amps quieter by fabricating a custom shield for the power transformers, going so far as to precisely position them by ear and by meter. Last, he rerouted some of the signal wiring for lower noise and made some grounding improvements. He did not want to make signal component changes as that would likely change the voicing of the amps. I also agreed. No trouble ever after that. Before I sold them to Kingrex, I took them back to Bob for inspection and asked him to replace suspect components. They got a clean bill of health and when both amps left Los Angeles, there were no (as in zero, none) mismatched parts in those amps. They worked perfectly, and by the way, Bob's noise abatement resulted in the amps testing -10db from as they tested before the changes, and -12db from Audion spec.
Now, Kingrex knows I have a long string of text messages from him after he got the amps, outlining that HE was inside the amps making changes on the fly, which I advised him not to do. He also texted to say at one point that after I coached him through an initial rough start that the amps were quieter than his push-pull amps and sounded "way better." Sometime after that some kind of trouble started and the amps got shuffled in succession to -- by my count followed here -- at least three other techs I know nothing about. Geeze Louise, he even ragged on the importers tech.
It's like every time you change dentists the new guy claims he would have done everything better than the last dentist and the one before that. But every time he claims any of these problems originated with me or Bob Hovland, he is deflecting, blatantly misrepresenting. Those amps left Los Angeles with no problems and all parts matched between them, included the many tubes I sent him above and beyond the deal. If anyone here has seen Bob Hovland's work, you'd know that what Kingrex is describing didn't originate in Southern California. Good luck with Electr-Print xformers. I just sold a couple of amps for a friend transformered with custom Electra-Print. Let's just say the Black Shadow pair I had were drum-tight in the bass region and lightning-quick by comparison. Audion's OTLs fall apart below 200 Hz? The amp is rated 24w. Well, I guess anyone can test them up to, say, 32w to see what happens.
Maybe you sent these to Bob before sending them out, and though they were in fine working order. I guess it comes down to your acceptance level of noise and issues. Up to a week ago, no one has been able to connect any front end component to the amps without a very loud ground loop hum. Which your answer to my complaint about this was to send me a couple Ebtech HumX ground lift cheater plugs. That issue has finally been resolved since I found this new tech. I can ground the amps as they should be. Would you like them back?
I have our text string too as well as a lot of other email with other people telling me what they saw inside the amps. Phil, you have the gift of gab. I'm sure you could sell sand to a guy living in the desert. But I trust the performance specs my current technician supplied. These amps were modified from where you had them by the Audion Tech, so I don't know exactly all he may have done. Maybe Audion added back in distortion. But I think something else happened.
The changes I had done by Audion were replacing the volume potentiometer with the Audion stepped ladder resistive attenuator.
I had the signal coupling cap changed to a VCap
I had the power supply rebuilt
I had the ceramic signal tube sockets changed to a German brand I do not know the name that is suppose to have excellent dampening qualities.
I had the 845 tube socket changed to one made from billet aluminum.
The flimsy tin plate the signal tubes mount to is now supported by Aerospace isolators used to protect circuit boards on space ships.
I really don't see how what I had done would have affected the bandwidth of a transformer. I thought that had more to do with the materials and manufacture process of the transformer itself. Maybe you weren't playing anything below 200 hertz. That can easily be done by adjusting the coupling caps. I found that out during my trials of getting the bias set right for the Elrod, ACME and Linlai tubes. There is a parallel cap around the bias resistor that limits the bass response of the amp. You had a 22 uf cap in there. The current schematic has a 47 uf.
Maybe you like distortions in your music. Maybe Bob knocked it down from where it came from the factory. I am not sure how changing the caps in the power supply would make that go to .5% at less than a watt. Maybe you couldn’t hear the deficiencies in the output transformer with all the noise. You were also running the tubes at very high dissipation rates. They redpated every tube I put to them accept for the psvane hifi and 1 shuguang. I think the shuguang C took the power. The bias was outputting at least 100 watts. You did tell me I was going to redplate some of the Shuguang you gave me, but the bias resistor could be adjusted to fix that.
The changes I had done probably revealed a lot of noise you were living with but didn’t realize was there. From this point on the amps were running stable but tubes were red plating and I was hearing the distortion issues that were most likely buried by the low quality stock components provided in the base model amps you purchased.
Locally I had the bias resistor changed and I had the 22 uf capacitor in that circuit changed to a 47uf. The cap change did lower the bass and I heard more slop and less control.
Last week I had the front end rebuilt. That got rid of the grunge (.5% distortion) I was able to hear when the better components were added to the amp. And it rid the amp of the ground loop. Thank god. I abhor nothing more than amps with floating grounds. It’s just wrong to cheat a ground. It serves other purpose besides safety.
I would love to have the Monolith Magnetics transformers. They don't fit. Electraprint do. I am using what is available. Once the new transformer are in, these amps should actually play to a very high level.
It has been a long road. I don’t suggest others take it. I would be very hesitant to ever purchase a 20 year old amp again. But I actually think these amps are going to work very well with my PAP Trio 15 horn so I am excited to reach the end of this road. 2 weeks from now and hopefully the rebuilds will be done.
If you say you did your due diligence before sending these to me, then fine. I accept you acted in good faith. But that makes me think you really didn’t know what you were using. You must not have realized all the problems that plagued these amps. But hey, we have debates all the time on these forums how our ears actually like the distorted noise tube amps make. It can be pleasing. Maybe your listening taste differ from mine. I like tubes. But I like them to be quiet and extended in frequency response. I spend my working days shedding noise from electrical infrastructure. So maybe I am sensitive to it.