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In Reply to: RE: 1958 Harman Kardon TA230 find posted by tbcblues on September 16, 2016 at 17:30:02
Start with some documentation. Use AA Email to "tickle" me and I'll send you some back.
The unit is good for approx. 15 WPC. The schematic shows 7408 O/P tubes, which are industrial 6V6s. The current production TungSol "reissue" 6V6 will be fine.
Along with other manufacturers, H/K used the "Cheap Charlie" method for low level mag. preamp DC heaters. :>( If the TA230 adheres to form, build a proper, regulated, 12 VDC supply for those tubes' heaters and install a RC bias network for the O/P tubes in each channel. Don't fret about space, as today's 'lytics are much more volumetrically efficient than 1958 parts.
Speaking of the low level mag. preamp, tape head I/Ps are passe in our current environment. Replace the source selector switch and directly wire a pair of RCA jacks to the low level mag. preamp, which is permanently configured for RIAA (phono). Switches in mV. level signal lines are highly problematic. Search the archives for my many posts about low cost Lorlin brand rotary switches from Mouser.
I'm biased and would replace the phono section with the tweaked RCA setup. A clear advantage to the tweaked RCA setup is the ability to drive a load. You would be able to "dub" your LPs, without fear of info. loss.
Eli D.
Follow Ups:
That is a nice little integrated amp. I still have one somewhere here, although it hasn't been out in years. It was the first "vintage" piece I restored. The last time around with it, I "borrowed" the current topology from Poindexter's Musical Machine of Audio Tropic fame. Those 7408 outputs are tough, sound good and last a long, long time so be sure they are worn out (probably not) before you look to replace them.
The mods Eli suggested will get the front end into the millennium and help greatly. A replacement of the electrolytics is a must. A sprinkling of modern coupling caps will help. I cannot recall if this had a Sprauge Atom in there somewhere but I did notice they have a pleasant influence on the sound. They are still available.
The O/P isn't really up to doing his own restoration of this piece. So he would need to have it done professionally. Since I've known Ken for over 15 years he's a vintage SS guy. But I always felt a vintage guy should have at least one tubed piece in the collection.
So perhaps the O/P could be helped if you could suggest if it's worth doing or just sell it. Also he has Altec speakers - could this stereo drive these?????
With Valencias it would be an excellent match. I used mine with those same speakers among others. Try your Sherwood with those speakers and see what you think.
Edits: 09/17/16
Very much worth doing a "restomod" and Mike Samra is an obvious candidate for the job.
The OP's Valencia speakers are plenty sensitive. 8 WPC is enough for 94 dB. sensitive speakers. The OP has speakers at least 3 dB. more sensitive and 15 WPC to feed them. Ear bleeding SPLs might be available.
Eli D.
Now it's up to you to decide if you want to keep this piece.
I use my Sherwood every day. It's nice to have a little tubed stereo around the house.
You got it for $50. So the restoration would be about what the unit would cost. Mike is obviously a fair guy. It ain't cheap but it will out last the both of us if restored. It takes a lot of hours and years of experience to bring these babies back up. And I'm sure it's going to need some tubes.
Unfortunately, this HK is not in the same ballpark as the Sherwood and never will be even with professional restoration.
I doubt anyone would even rank this in the top 10 of vintage tube receivers. IIRC, the tuner section on these is actually mono with a provision to hook up an external multiplex.
And if you don't really need a tuner the list of better integrated amps is even longer.
If I was going to spend hundreds of dollars to have something restored I'd suggest starting with something that had more potential.
"IIRC, the tuner section on these is actually mono with a provision to hook up an external multiplex."
That is easy enough. DIYer extraordinaire S. Bench to the rescue.
Eli D.
No, not a problem. It's easy enough to add a multiplex but it is an additional expense. I just wanted to let the OP know that just because the amp is stereo that the tuner sections on some of these early receivers were sometimes mono.
Personally, I like mono. When I listen to radio it's usually with my Sherwood S-3000 mono tuner connected to a mono SE 6V6 Zenith console amp driving an Altec corner cabinet loaded with a 604C driver. Unfortunately, I can't find much worth listening to around here.
You'll Laugh but I have that chip kicking around the house.
.. I find it interesting that Valencia datasheet did not specify a
H.F. driver ..
Willie
Because it dosen't. It's a two way with the horn driver going out to about 14k htz. I us a Fostex or EV horn tweeter to extend the highs as I see fit.
... I meant the datasheet did not specify whether the H. F. driver was an Altec 802, Altec 806,Altec 807, or Altec 808.
For my Valencia's which were original Valencia A's, but I modified the cabinet to have the two big side vent tubes, and they use Altec 806 for H.F.
The Altec 806 has a shorter magnet, not as long as a 802,807 or 808.
That helps to explain why Valencia's need help on the High end.....
sometimes. YMMV .
Willie
Will
Open the linked thread and scroll down. I have the same in the utility cabinet but came with 806 HF drivers which appeared to be original to the horns. Many mods later, they are closer to a model 19.
Thanks Mike
That was a very helpful link. .... With my (reconed to 416) Altec 421 L.F. Woofer, my Altec 808 H.F. drivers and my now Dual ported 846A cabinet....
I'm now calling my Valencia's a Valencia B ... AKA 846B.
I won't talk about the crossover....
Willie
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